Hey guys, so I got around to putting a new catless downpipe onto my STI...(sorry)
I just replaced the factory part, and kept it in case I want to go back. The car is otherwise completely original. The change has been fantastic, boost comes on almost 700rpm quicker and you can really feel it. However my boost now spikes to around 18-19 PSI (according to ****ty test boost gauge) where it was just a little over 15 PSI before.
I've been doing a bit of reading, and people seem to be divided about this mod and the safety to the engine. Some say with stock muffler and intake it is ok without a tune on the stock ECU, others say a tune is mandatory because the turbo will damage in boost spikes.
The guys down at crowe sport have said to "modify the restrictor so that youve got 15psi and you will still get the benefits of quicker turbo spool, which is the main advantage of the aftermarket downpipes. If you wanted to spend a bit extra you could get an electronic boost controller, this will allow more accurate boost control"
If I wanted a proper tune I would need a new ECU yes? Anyone had experience with this issue? Any help is appreciated. Of course I want to keep the car as unmodified as possible!
Cheers,
Fraser