I decided to buy a de-cat pipe and back box for my 2000 STI import thinking of all that extra BHP and sound. It is a Haywood & Scott. Excellent!!! The only disappointment was that when I looked at the old pipework, there was a silencer where I thought the second cat should have been. The old pipework is puka standard STI stuff. So I feel a little cheated. It sounds better but not much quicker. If this is normal then a word of warning, This isn,t a cheap way of getting more power when youv'e got an STI.

 

not just the sti ...my jap spec wrx wagon also just has the one cat,has a resonator box in the center pipe where there would be anpther cat on a uk car

 

Lesson to be learnt, take 1 min to have a look under your car first before parting with any cash!! Harsh but true. Try a decat downpipe, you will notice the difference with that.

 

On my STi3 wagon the centre pipe had a resonator which, from the outside looks identical to the cat version (which I bought for MOT time). The only way to tell is to look inside, the cat has a mesh across it and the rsonator is a plain hole.