Originally Posted by
controlliner
Modding an engine is fun but if you do not have a dyno, you will never have comparisons or figures to see what worked or not. Hearing is not always an accurate way to judge your mods.
A GPS and a Tachometer will tell you if what you did made a difference of not. If the modifications are done to change the powerband (usually moving it higher in the rev range), you probably will be able to hear the difference too. The Picco .28 I modified had a notably higher top rpm that you could hear. This engine probably picked up 2000-4000rpm on the top end without sacking the low end punch. At least in the truck I put it in anyway. But overall, I agree that it's hard to quantify your results without some sort of scientific way to measure it. Changing the manifold and pipe can change the exhaust note and make it sound more powerful, but it could just be that - a different sound.
With these engines, the manifold can have a more significant influence than the pipe or even the fuel (more nitro or less oil).