If I was to fab up a short downturned testpipe coming from the header collector, that I could easily swap back to the streetpipe/silencer, would that negatively affect performance without some tuning?
I'm sure it would beF1 car loud.

 

Oh yea its an 02' F4i

 

Yes it will, going from exhaust to no exhaust ... just a pipe will change the fuel to air ratio and not give you what you're looking for. I'm not an engine expert, so you may need better advice here, but it could damage or at least shorten the life of your engine. I mean your plugs are going to wear out faster and your engine will build up carbon faster screwing up the valves and so on.... like I said, not an expert, but from my limit knowledge, I wouldn't do it unless you have a PCIII and a map for each setup.

 

yah, it would be great if you had power commander to change map but if you cant tune it for the new downpipe i wouldnt do it...

 

Ok well, I'll try getting a Power Commander and tune it. I'm assuming no backpressure from an exhaust would lean it out?

 

Any exhaust change will mess with the fuel/air ratio, one as extreme as no an open pipe needs to be mapped.