since you're the one that revived this thread, i'm guessing you're the one that needs help.. LMAO..

Yes.. to answer your question plainly.. You'll be replacing your Cats w/ straight through test pipes.. You will get a LOT of sound, because there will be nothing there to resonate the sound. Cats have coils to filter the pollution from the exhaust cleaning the exhaust air going through them from the headers.. Test pipes do not.. That's why they normally trip the Check Engine Light, because the O2/pollution ratio is not satisfactory to the O2 sensor.. Most states, you won't pass inspection w/ test pipes and the smell of gas coming into your car is ABSOLUTELY HORRIBLE..

Oh, by the way, this is with any brand of test pipes, not just FI.. I actually like their products.. This isn't a subjective review on them, just an objective view of test pipes in general.. Some people actually like the smell of gas coming into their cars.. (shrugs)


You will also get power as well because like I said previously, you're replacing the most restrictive part of your exhaust system with the least restrictive option, straight through pipes..

You should really weigh the things I've told you versus the power and sound gains.. I think HFCs are the best compromise.. I have these myself, and you get none of the cons that I've mentioned w/ ALL of the benefits - 1 or 2 horse power. You get the nice sound, and power, minus the smell, check engine light, and MOST IMPORTANTLY, you'll pass inspection.

Hope this helps.

EDIT: Just thought of someting else.. I also have a 1/2" spacer.. Where as the 5/16" is great for power and getting more air to the 2 under-utilized front cylinders, the 1/2" adds a nice growl and deep rumble to the ride that is audible.. I also noticed I was idling lower as well when I added it, so the sound was deeper and LOUDER at WOT.. I had my spacer before I added the HFCs so I could tell the difference.. Also, after you get either of these, I'd advise you get a tune, possibly increasing your timing by 2 degrees.. will give you a nice bit of pep to your accelleration.. And optimize your car for all your air mods.