So Iv recently purchased an sti wagon. Yet to collect. Now the previous owner ( my sister ) they fitted a full decat bar the up pipe and a hks air filter. It hasn't been mapped since the changes. What kind of effects does that have on the fuelling/boosting etc? Now when I get it in going to go over it fully. New cambelt, leads, plugs full service etc. And will get it mapped once that's all sorted. Any advice/help greatly appreciated.

Dave

 

Decat sometimes makes the turbo over boost and can cause a fuel cut situation, on hard acceleration of course. The fuelling might end up lean as well, not always though. My experience of the 1997 8S ECU is that it's very rich and can cope with a full decat on the stock map. It does over boost though. Probably best driving it easy until you can get it checked out properly.

What year is your car?

 

Thanks piehole for the reply and the advice. My sister never drove it hard tbh. I doubt she ever put her foot flat to the floor even. It's a 94 plate classic wagon. Would like to fit an up pipe aswell so would definitely get it mapped when I fit that

 

Brought my blobeye with a decat and wasnt mapped. Ran fine although i was always worried about it so never really gave it alot and didnt put cel light on. I had it mapped by andrew carr for piece of mind more than anything. Im sure your car wouldnt have cat in uppipe anyway mate.

 

don't waste your time fitting the up-pipe the one fitted to your car if in good condition is perfectly adequate for your needs, only newage wrx's had a up-pipe cat fitted.