What is the stock horsepower of a 5.7 Hemi.....4X4 QC 1500 stock.....how much does the flowmaster dual exhaust add??

 

It's rated at 345 HP. Seriously doubt that the exhaust would make much of a difference other than sound.

 

rule of thumb is 15% for drivetrain loss so figure around 294-299whp. I actually have plans to dyno my truck before slapping on my new intake so I can get a real baseline.

 

I am not stating fact with numbers to back it up OK. The local performance shop told me I would be wasting my money on my 03 to change the exhaust, however, they did say that if I had an 04 that it would be more beneficial. I have no numbers to quote just the fact the guy didn't want to take my money, which I would have given if the exhaust would have made a difference.

 

Da hell? That makes no sense. The only real way to make more power is by forcing or increasing the amount of air a vehicle can "inhale" at a given moment at the same time evacuating the hot gases as fast as possible. Simply put, the faster you can move air into and out of your vehicle.

 

The drivetrain loss is more like 20%. You can expect around 280 RWHP on a dyno with a stock Hemi. The exhaust might add 2-3 HP. Combined with a CAI though you might gain 8-10.

 

I got 272 WHP with mine when it had just over 3K miles on it. There is alot of variation with these chassis dynos, but the local one here said 20-25% drivetrain loss for an automatic.

Due to the top speed limiter you'll have to test the truck in 2nd gear, which they said makes a difference as well. Let us know how you do.