I've noticed since I switched out my exhaust with the dual flowmasters I have gotten more out of my gas! Now that can be a big factor in keeping your car a daily driver while still making it that much better. So just by switching my exhaust it is giving the engine more room to breath with the bigger pipes and is really helping.

If you are not satisfied, then you can try the power extractor engine which can help you . This is simply the addition of an exhaust pump,the 2nd phase would be to convert any standard 4 cycle to standard 2 cycle by adding the exhaust and intake pumps.If interested can visit power extractor to know how this engine is different from other.