- Got my 4" exhaust done from downpipe back. Straight pipe. And wow, what an upgrade! Had 3" straight before, and could only get about 8.5 psi from my 088 before my EGTs were in the danger zone. Now I can get 12 psi while only maxing out at 1100°. Both results from driving up the same long, fairly steep grade, pedal to the floor, unloaded. Ambient air temps around 60°. Time for studs! Also isn't much louder than the 3", just throatier.
I'm surprised that it makes that much of a difference since you maintained the 3" DP. Wish I had known before I built my 3" straight pipe like a month ago