I took delivery of my P1 last december and within 1 month had put a full HKS exhaust system on decatted. After listening to recent debates about the possible damaging effects the decat could do without having an ECU remap I decided to take the downpipe off and refit the cat this weekend gone.

Took the car for a spin this morning and I must say I'm pleasently surprised! It seems just as quick as it was only 10 times smoother!!! It's like going from rough, jagged and on the edge to a refined, smoother ride. The forge VTA dump valve seems to thskkkkk for longer too!

I've lost the raspy growl of the HKS exhaust at high revs but it's kept the deep note sound which to my mind sounds purer and should also please the neighbours.

Eventually I'll go down the remap and decat route again but that's after the warranty has run out. Car had it's 1st birthday on saturday so only 2 more years to go!

Summary :- If you're worried about blowing your engine up it's not that bigger sacrifise to make

 

I went to Subaru and they were due to fit a decat downpipe and mid section, but the main guy said that it would produce the check engine light as the sensor would detect there was no cat.

In the end I came away with no downpipe and mid section replacement. Anyone any thoughts on this ?

 

The sensor for the exhaust goes in before the cat so I don't see how the car could 'sense' it.

 

the decat downpipe on a p1 would produce no warning light, i used to have a p1 with a full ss system, after reading the threads about engines going bang , i too would have replaced the cat downpipe, i put the standard exhaust on the car to part x it, it was terrible, strangled of power, no torque, no noise
so far all ive got is a ss back box on my sti7, waiting for my ppp due in jan/feb
mark

 

The CEL on decatted MY01/02 is well documented in the technical forums, it doesnt produce a CEL on decatted classic shapes though.

Do a search there is plenty of info on it