[NHRABill]

This post went awry... From a statement of changing exhaust and tires to see fe improvement to the defense of sorry don't believe anything till it is proven.

Don't take this the wrong way but the prove it defense is childish. Engines are very complex and depending on the setup and combination you are using an exhaust can hurt or help you. Some engines sacrifice performance for smoothness or quiet some sacrifice fro performance and still others are tuned for efficiency from the factory. Can they be changed? Yes. Can improvements be made? Yes. But it depends on what areas you are looking to improve.

Depending on the test and your needs changing the exhaust to suit your driving style can yield an improvement. Welding up a set of equal length or long tube headers is nothing new, porting and polishing your heads , intake runners or plenum are things that also improve the engine flow increase performance and power. Do I need to prove this or can I use that this common knowledge to any shade tree mechanic or person who likes to work on cars. Increased engine performance takes less gas fro a vehicle to get to seed using less fuel but when at speed it consumes more gas quickly negating the initial improvement in efficiency.

I increased the exhaust size on my truck because it rarely goes more than 50 miles in a week. The top city speed is 40mph on my daily drive and my OD gear won't switch till I hit 45mph. the gain in torque by the larger exhaust was a welcome addition to my situation.

There is no correct formula that applies to every engine they all have variables.