So I finally got my exhaust done, original muffler was clogged up with soot pretty bad. when i got it out I could tap it on the ground and about a tablespoon of soot would dump out each time. So I got 2.5" from the down pipe right above the first turn into a 3" in and out flowmaster and 2.5 tail pipe. This is in my turbo trooper and wow what a difference. My original mileage stock was right at 25mpg per tank give or take a half a mpg, running b20. I added a secondary air inlet to the air cleaner and both inlets collect air right in front of the core support instead of the factory snorkel. K&N air filter, and now the exhaust. I'm up to a solid 27.5 mpg with two tanks so far and the power increase is amazing (almost all city driving). no flat spot before 2200 rpms anymore and it spins up VERY quick to 3200 rpm and redline. Noise wise its great a tiny bit louder than stock but just barely in the cab, hardly noticeable. Outside its a little throatier but not loud by any means. Before the old exhaust was a steady stream of hot air, now each pulse can be felt with your hand a foot back from the tailpipe at idle. Anyways it was pricey around 300 bucks including a new flex pipe but what a difference in drivability. this rig is beginning to have some get up and go, gets up to freeway speed quite nicely, strong passing power... oh the 4:10s helped out big time as well, lets the torque do what its supposed to. Down the road I see an electric fan, evans coolant, a n/a head i have with the bigger valves, maybe intercooler and a slight fuel adjustment... Oh to have more money and time.
Anyhow my 2 cents.
Hope to see some of you at the west coast meet