sk515
Here I come to save the day! 
5Zigen Fireball...I"m very happy with...I have the Japan version, It comes with a silencee, and my car having a gutted cat is unbelievably loud w/o the silencer, so with the silencer off it's sound is very deep, kind of like a motorcycle (1200cc)...nice and deep.
But performance wise, I think this is the best flowing exhaust systems out there... A friend of my mine who own and operates a Machine Shop where they flow test heads, flowed the 5zigen vs. Greddy exhausts. And I was under the impression of buying a Greddy P/E or Evo, because of there reputation, and since, that's the same exact thing that I have on my 4g, but after the comparsion (flowtest) of 5Zigen vs. Greddy...the 5zigen out flowed the Greddy by a good 25%-30%, so I was sold.
My car with silencer off, man vtec....is unbelievable....ask the micrew. I have one of the fastest 5g (OBD 2) Prelude's in the Mid-Atlantic!
Very happy with 5Zigen Fireball.
thanks..
vnt
