I have my second "I'm tired from lack of sleep, here is my dumb question" question for the day.
If exhaust is going through smaller openings out of the engine, combining together into a "medium" size pipe, and then getting put through, say a 3" downpipe (even bigger) and then reduced down again to stock exhaust after the u-bend, how is the bigger downpipe helping?
I've installed a TDC FWI, front PLOG, and a 3" catted downpipe in my 2000 GTP, and have always wondered this. Maybe it is just me being tired, but it seems that air is flowing nicely until it gets past the downpipe and then gets shoved into a smaller opening. I know that the 3" downpipe has a reducer on the end of it to make it 2.5" to hook up to stock.