Originally Posted by MMZ_TimeLord
Sounds like he's eliminated almost all the back pressure. He's going to need an ECU tune to be able to compensate for that without damaging the engine.
nah ... its a turbo car, it does not need backpressure ... on a NA or supercharged car the only reason to not have a open downpipe like that is to keep the valves from cooling too quickly and cracking in time. on a turbo car you can run a open down pipe just a few inches long off the turbo and have no issues ...
this will actually extend the life of his engine with no further tuning as SRT-4s see high EGTs with any restriction on the exhaust which have been known to melt the cowl and begin to damage the valves ... with a open exhaust like this it should see a good drop in EGTs.
added: also having stepped primaries and a proper collector on a NA car can lead to impressive power gains through exhaust gas scavenging if you utilize a more aggressive cam with a good amount of overlap...