which one is good sound and gain power. which brand?

now i use test pipe 2.4 inch is too big or not? what size appropriate ?

now i plan to buy HFC is ok or not? if compare with test pipe


I don't like the sound around 3000 RPM up is look liket the V-tec in HONDA 55555

Now i use AMUSE R1 Titan cat back the sound great but so terrible only 3000-4500 RPM

thanks' a lot guys

 

if you can pass inspection, get the test pipes... if not gutt your cats and put non-fowlers to take out the cel light. or just the hfc and get less gain with more money