johnski

im looking at getting a hayward and scott full exhaust on my bugeye wrx, is it worth getting it de-cat? or should i just leave the cats in? does it make much difference to the power de-catting it?

scotty boy 80

iTrader: (5)

Peronaly I just prefer the cat-back system, gives it a nice tone without doing your head in on long runs or motorway miles......thats just my preference tho

dynamix

iTrader: (3)

Makes quite a lot of power difference. Assuming you are having it remapped it could be around 30bhp difference.

Alan Jeffery

If you intend to performance tune it, removing the cat is the first priority, as it restricts everything you do otherwise. If the object is to just make it sound nice, then a cat back system will be fine, and won't require any other work.
If you want to remove the cat, you have to arrange re mapping, or there won't be any point to it.
You'll have to put the cat back for the MOT. OR you can fit a sport cat. A 200 cell one, such as the Prodrive or Milltek version costs around £500. There are cheaper 100 cell sport cats which will pass an MOT if the engine is properly warmed!
In actual fact these cars have three cats, one before the turbo and two afterwards. From the initial tuning perspective, the after turbo cats are the ones to remove. Moving on from there, larger turbo etc, you'd want to remove the up pipe cat as well.