Rich

Tried that (ok it was a dry stone wall). It didn't work.

Tried that (ok it was a dry stone wall). It didn't work.

Hi Rich,
 
It would be £10.00 for additional adjustments (both sides included) to the front and £10.00 for the rear. I hope that makes sense.
Thanks
TunedUK

Thanks man!
Not changing wheels, just going up to 9.5" on the front as I love the concave!
Video of the TD UEL and the CGR Exhaust:
 

It is. Shark tuned to 282bhp, Bilstein and Eibach suspension, ARB's, bigger brakes, etc. The pull in-gear once back 2500rpm is great. It's only weakness is getting power down so requires a disciplined right foot. But this means inputs have to be precise which in tun makes me better. I found this with the 86 too. If you are precise with it, it's rewards you for it.    

Mine:
Audi A3 1.6 - first car, solid enough, but not good on fuel for the performance. Audi A3 2.0T - much faster (200 bhp and quattro), even thirstier, but at least it went well. Actually pretty cheap to run as it only lost about 1k a year in depreciation. Audi S3 - bonkers fast (300 bhp and quattro), lovely DSG gearbox, a bit boring dynamically. Put it through a wall. D: Toyota GT86 - best car by far, much more fun than the rest (despite being much slower than the S3). Bought with the gap insurance payout from the last car.

Short and simple list for me:
 - Get car back from bodyshop
 - Try really hard not to have an expensive off again!
Joking aside:
 - Fit TRD rear spoiler and debadge boot
 - Fit oil cooler and oil pressure sensor, add low oil pressure Racerom derate.
 - Change ride height and realign (its too low at the front and too high at the back currently)
 - Design and fit heat shield to stop P0351 fault code on track days

Nothing has happened to it, but it's still got the 1320 whistle. I'm thinking I'll try to get new flex pipes welded in.
Also, I'm thinking oil cooler.

I've only got 2 definite jobs at the moment:
MOT Swap to Summer wheels Other possibilities:
Fit oil cooler Get it detailed Remove side stripes I've convinced myself I need to be good this year and start saving some money.... how long that idea will last I don't know.
 

My Custom Hayward and Scott Cat-Back Design and Proving
 
Introduction
 
**If you don't want to read at the theory, skip to the end where there are pretty pictures and a video**
 
Firstly I should point out that I am a bit of an old man and dont like noisy exhausts! LOL. Please dont take any of the following as a criticism to any aftermarket exhaust; I just wanted something that is quiet under full throttle until higher up in the revs. This then gives me some headroom to further modify the exhaust.
My current exhaust, the Cosworth Cat Back, measures 92dB supercharged or 89dB N/A, so not particularly loud but when cruising on the motorway, 6th Gear, 3k rpms and going wide open throttle, I found it to be very boomy in the cabin when it was hot, particularly after a track day. Even with cruise control on when coming to a hill, the slight throttle was enough to annoy me on longer drives which are becoming more and more often in my GT86 these days. How on earth some of you live with 100dB exhausts is beyond me!
Its not a criticism of the Cosworth cat back; I still think it sounds awesome and I haven't come across any other cat back for this car that is quiet when under WOT at low revs either, apart from stock. Certainly it's not any worse on the Cosworth 0.1 than other exhausts I have sampled in the 92dB range.
Silencer Theory
 
Straight though absorption silencers used in most aftermarket exhausts dont attenuate sound very well at low frequencies. It depends on the length, volume and packing material but generally they dont block as well at lower revs as they do the higher.
The reason for using these silencers is that they dont restrict flow like a cambered silencer (stock).
I decided to do a bit more research into OEM silencers and how they work. It turns out that a stock silencer typically has two or more chambers inside but each chamber often has a different target frequency range.
I am not going to get into detail but here is a diagram of a typical 3 chamber silencer. Each chamber is a different design targeting different frequency ranges. 

And here is the insertion loss of the different straight silencer types:

The tuned pipe, otherwise known as a branch resonator or sometimes mistakenly called a Helmholtz resonator is quite a popular DIY for helping drone.  Its length is designed to reflect sound waves 180 degrees out of phase at the target frequency. The result is noise cancellation but the Q is quite high so it doesnt have a very wide range.
At the target frequency of 100Hz and 150C gas temperature, the pipe would need to be about a meter long! Here is one such example (borrowed from the ft86club):

I had noticed that some Cat Backs do have Helmholtz resonators, namely the ARK Grip and HKS HI Power Spec L. I havent heard either to comment other than to say, looking at my calculations and the images, it looks to me like they dont target 100Hz as the cambers are a bit small and both seem a bit loud for my goal.
The Helmholtz does look appealing though, as it has a lower Q, so wider attenuation range and the packaging is much nicer requiring a big air chamber and a neck, bit like a bottle.
Hayward and Scott
I decided to speak to Ian at Hayward and Scott about a custom Exhaust as I have always been impressed with their work. Originally I asked Ian to make me a large single absorption silencer like the Q300 or Miltek but to connect up to the 3inch Cosworth mid pipe. The intension here was to add additional resonators in the front or mid pipe if it was still too boomy at low revs.
After some discussion with Ian I decided that it was better to start with a whole new cat back rather than chop up the current one as Ian was sure he could get a much larger center silencer in the tunnel.
We decided 70mm (2.75inch) pipe would be a good compromise and we should keep the Y design as it has the best flow. He also explained that they have a small chamber built into their silencers too which may help, so I left the car with them for a week while they made the system.
Here are some pictures of the finished product:




Ian has a catalog of exhaust tips but I liked a twin wall rolled and these with the perforated inner did the trick. Actually, originally I said I wanted a design similar to the Cosworth/Nameless/Perrin but Ian fitted the rolled and I decided to keep them when I saw how nice they look. Ian knows best! J
The results were very good. Much quieter and a pleasing rumble, however on the drive home I wasnt quite happy with the 3k rpms WOT boom. Although far quieter than before, I wanted even less, but the top end was perfect.
Helmholtz Design
 
I decided to look in detail at a Helmholtz resonator design.
First port of call was Wiki!
https://en.wikipedia.org/wiki/Helmholtz_resonance
Next I made a spreadsheet to calculate the required volume and neck lengths from the formula on the wiki page. At this point I want to thank the few engineers; Frederik, Dan and Matt who checked my sums weren't completely wrong!
Also another good reference was a paper discussing using the muffling effect of Helmholtz Attachments to a gas flow path
http://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=2200&context=icec
I decided to copy the ARK style arrangement, with two Helmholtz resonators mounted in parallel to the rear silencers as this was the area under the car with the most space. Also two would work better than one. They would be quite a bit bigger than the ARK design though, targeting 100Hz.
Once I was happy with the design on paper I made a mock up from cardboard and plastic pipe to check it could fit where I had space.
The only real issue going forward that was highlighted could have been if I got the gas temperature wrong, as I had used a thermocouple in the exhaust pipe which wasn’t right at the point the resonators would attach. I measured 150C which I though was realistic near the back boxes.
So back on the phone to Ian at H&S to get the Helmholtz chambers made up and welded on the existing pipework. Ian managed to tuck them up a bit so from behind you still see the nice H&S boxes
Here are some pictures. I think it looks awesome!




The result is a reduced 2-4krpms noise and just a nice background rumble when WOT @3Krpms.  And to show the effect of the Helmholtz here is a graph of before and after:

There is about a 10dB reduction downwards of about 100Hz (3k rpms) which equates to sounding about half the volume. In terms of how it feels, the noise power is 10 times less!
Finally a little sound clip
 
Final Specs are:
·         When hot 83-85dB @5k rpms (45degree, 1Meter), though at Bedford they told me it was 79dB.  If you N/A reduce this by about 3dB.
·         70mm internal pipe diameter splitting to 2x50mm pipes
·         Low level hum when WOT at 2k-3.5k opening up to a nice refined tone above 4k
·         Y design for a smooth gas flow
·         Stainless steel with a lifetime warranty (check website for terms and conditions or talk to Ian)
·         UK made
·         Personal touch being able to select from a range of exhaust tips
Well thats just about it. This was much longer than I intended but I am very happy with the results and wanted to share my findings.
Thanks to Ian for his craftsmanship and help designing this amazing cat back, and also for his quick responses to my emails over the last 3 months! I cannot recommend highly enough.
H&S also do a selection of 2.5inch options with different middle silencers (or none at all) that are worth a look.
https://www.haywardandscott.com/toyota-gt86.html
If anyone has any questions, do feel free to ask away. 
**edit - added pricing**
So pricing looks like this:
Cat-Back with 70mm piping and the extra larger center silencer £650 + VAT  Exhaust Tips of your choice: Varies but roughtly ~£75+VAT Helmholtz Resonators: £275+VAT Above priced are fitted. 
ease note this system differs from their standard offerings in that it has 70mm pipe diameter and the extra larger middle box is bigger than their "larger center silencer" on their website. 
If in doubt talk to Ian at H&S about your needs.
 

Obviously it would only become an issue in engine failure instances, and even then it would be a case of proving that the cooler was the cause of the damage.
There is no black & white policy with Toyota Warranty. 
Remaps & forced induction I would suggest as voiding the engine warranty in my opinion.Even then it could be open to discussion.

The joy of modern super safe crash structures. A pain in a relatively light impact like ours, but a life saver in a much bigger off.

I ran power back from the central console for my efdc in the boot. It's pretty easy - remove the central console (instructions are around on one of the forums) and you can route wire along the top of the transmission tunnel easily. Wires will go under the seat backs of the rear seats  and into the boot.

If you spin the bolt too far it may slip and no longer be aligned with the screw threads. You can get it back in, but it requires removing the headlight motor (which generally requires removing the headlight). It's fixable, but a pain.

If/when mine cracks I think I'm going to get something else. They just seem poorly made.

Yeah, it looks like its mostly cosmetic, but will confirm for certain when they get it stripped. As well as what was visible from outside and with the bonnet up, bouncing across the grass on the way to the wall has cracked the plastic undertrays behind the metal sump cover. The bonnet itself looks okay and just needs rehanging on the hinges. Still getting them to respray so it blends well in to the new wing/bumper and its stone chip free again :-)

After much searching I finally found a relatively nearby bodyshop (Finishline in Graveley near Hitchin) who knows what they're doing to fix the damage from the Donny trackday.. I've been shocked at how bad the customer service has been in responding to requests for repair estimates at lots of places, god knows how they stay in business.
I dropped the car off today and had a guided tour round by the owner Chris Bray, they've got a real mix of historic cars they're restoring - Mk1 Lotus Cortina, MGB with a 400HP V8 conversion, 1930's Bugatti etc etc, they clearly know what they're doing, are passionate about cars in general and have a long waiting list so I'll feel confident my car is in safe hands. Just the long wait until late February to get it back now.
I'm taking the opportunity while the damage is repaired to get a few cosmetic bits tidied up as well and to lose the optional chrome trim parts the dealer I bought the car from had added, the centre of the fender garnish will be gunmetal grey to match the wheels which should look 10x better.
The battery finally died a couple of weeks ago, I've replaced it with a 70Ah Bosch S4 battery, so much better than the standard Panasonic battery and as a bonus it has a blue top which matches the car nicely.
Just need the weather to warm up a bit so work can continue on the Puma rally car and keep me occupied until the BRZ is back, we're rewiring and replumbing the whole thing from front to back and swapping the terrible current pedal box for a floor mount OBP item, its a nice piece of kit and much cheaper than the likes of AP/Alcon/Tilton etc, pic of the Puma below for those who haven't seen it yet.

Ah, I just use airdroid to drop it across to my PC.

Just held in place with the water lines. You need some flex for when the engine moves. If you bolted the laminova there would be no room for flex as there is only a small amount of pipe at each end.

Yes but the coolant pipe the laminova is spliced into is at the exit of the radiator. I've never measured it myself but it may be cooler than the point where the sensor measures it.
If the water coming out the radiator is indeed 90C then the oil should be above that.
I can try measuring it with an IR meter when I get a chance.

I'm hoping/aiming for 85c+ for daily driving/coasting on motorway, ideally closer to 90c if possible. Might actually do some research before fitting my oil cooler... blasted impulse buys!

I think you'll struggle to maintain 95C steady state but high 80s would be my guess.

@nerdstrike All true, however it's not quite as straightforward as needing a percentage more cooling. Summer oil temps are actually not much above winter oil temps from my observations. Which makes sense when you consider that most of the oil cooling effect at present is dumping heat into the block which is removed by the coolant. My coolant temp is the same year round since the radiator is adequate to maintain it and thermostatically controlled.
The numbers above are really just to get an idea of target temperatures for oil in normal driving. It seems like around 95C is a good temp to shoot for.

Mine hadn't.

I did some logging on the way home today. Mostly B roads with a little dual carriageway. Oil temps settled at mid-90s once it was up to temperature. 96C on the dual carriageway at around 70 was the maximum recorded. Temperatures stayed over 90C even when pottering around town after coming off the bypass.