Very few options in modding an ISF, I have the Joe Z Exhaust and it's very nice, but it depends on what you like, jump on you tube and check out all the exhausts, HKS, Borla, ISS, PTS (Joe-Z), all have different sounds, and that's what you'll wanna judge by, the hp they give you doesn't seem to change much, i think i got 13hp from the Joe-Z pipe and drop in filter, with the exhaust.
also most custom exhausts built and displayed on the forums, (which might be a cheaper option) sound like the ISS exhaust (imo) because i believe they use the same mufflers (magnaflow?)
Also i bought the PPE headers as well, but both Sikky and PPE have shown 30-40 hp depending on the car. I can tell you PPE and PTS (Joe-Z) have unreal awesome customer service.
also most custom exhausts built and displayed on the forums, (which might be a cheaper option) sound like the ISS exhaust (imo) because i believe they use the same mufflers (magnaflow?)
Also i bought the PPE headers as well, but both Sikky and PPE have shown 30-40 hp depending on the car. I can tell you PPE and PTS (Joe-Z) have unreal awesome customer service.
