I am going to de-cat my MY99 STI type R, which cat's should i remove, I already have a Trust back box fitted to the car. Just need some advice on wether to remove both front cats or just the centre one?? Also will I have to hav the car re-mapped straight away or are MY 99's ok? Also any recommendations on which de-cat pipes??

Thanks in advance

 

I'll be watching this with interest, I have a S/S de-cat centre and back box and would also like the down pipe but don't know if I will need to have a re-map. I also own a MY99 ( uk )

Steve.

 

Tiss,

You don't say whether the car has been re-mapped already. So I'm guessing your running with Optimax+Booster. The cheap way would be to get an Air Fuel Ratio gauge, then when you decat you will be able to see if it is running lean, if it is then it will need a re-map.

For a MY99 UK car, I ran mine with a full decat for 50k with no problems and no remap, just always used Optimax.

 

As above on the UK model mid-cat gives minor gains top end but is mainly just a bit more noise and a lot of hastle at MOT time. From my experience and lots of thread reading/advice front and backbox will suffice happy with mine both Magnex can only speak for UK though.

 

BTTT.

 

a 99 sti will only have one cat in the down pipe the other box in the down pipe is a resonater (i think) should be the same as my sti v4 , just replaced the down pipe with a haywood & scott pipe with massive gains