Darth Raknoor

Will definitely look into those, thanks. 🙂. Nice wheels by the way, really hope when this virus is sorted I get to meet up with people from here at japfest or an other event and see all your 86's/BRZ's. 

Seriously go with the Reyland AP 4 pot kit with their discs and save some money over the AP discs. It's more than up to the job whatever you throw at it. Mine fit under my 17x8 ET38 TE37's, with loads of clearance. 

The +35 offset will give you more clearance, not less.

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A church said, you do not require to change suspension to use a BBK however, if with you current choice of tyres you can lock the wheels its pointless fitting a BBK. If however your using stickier rubber and you cannot lock the brakes with them then a BBK will give you increased performance.
 
For reference have the Rayland 330mm kit:
http://www.reyland.co.uk/subaru-impreza/
 
It fits under my Rota Boost, 17x17.5 E48 with a 15mm spacer. It also fits under my XXR 527 18x8.75 E35.

I was just looking at Work wheels as an alternatively for you, as they make the T5R which is the same style as the Advan TC4.
You can get the works from Driftworks. I'd speak to them and see if they do them in custom offsets as the standard ones listed are very weak. 
https://www.driftworks.com/work-wheels-emotion-t5r.html

These are 17x7.5" et35

I think as long as your going for 18's there shouldn't really be a  issue. Ap's own site states they are designed for 18" wheels (provided your going for the 6 pot). Not sure about how the ET or width would effect it but if its only a 7.5" you could always get some extra clearance with spacers ¯\_(ツ)_/¯

Don't know why no one has recommended this so far but this is by far the best tool I've ever seen to help explain ET, size etc. Pretty accurate too!
http://ft86motorsports.com/wheelitfit/
Just bang in what you want and see what it looks like compared to the standard set up.
 
Also nice choice of wheels  I'm looking into getting some DR10 work wheels 18x8.5 et32. Gunna be super close and might need a bit of adjustment but they look so sweet. The most unspoken thing I notice, since everyone points out 'poking out', no one seems to mention if you have too wide wheels with a high ET your wheels will catch your suspension. A friend of mine had a insane amount of jap wheels lying round and we where trying some on my car, he had some green D9R 18 x 10.5 et 48 and they couldn't even touch the studs because they hit the shockies about 2 inches before the start of the thread >.<