So we have mufflers, test pipes, HFC's, catbacks. I'm not so familiar with the G37 exhaust system as I was with my old car. Are there any exhaust systems which replace the test pipe, and need to replace the stock cats for HFC's? A diagram would be awesome, because most people say "I got this exhaust system, etc...", but don't speicfy which company makes an actual complete exhaust system or just a muffler. My confusion is based on my experience with my old WRX where there were certain components of an exhaust system (downpipe, up-pipe, catback, headers) which were replaceable, but all of those would be replaced by a turboback exhaust system (exhaust headers). Any help is much appreciated!

 

a Cat back exhaust such as the borla or HKS High power and a set of HFC's is a complete replacement of everything from the headers back. Test pipes and HFC's are interchangeable like boots and shoes. Just depends if you want to wear boots or shoes.

 

I prefer boots, of course.

 

Main differences between a test pipe and HFC? Is a test pipe just a straight pipe (no cat)?

 

yes test pipe has no cat its jsut a pipe or a resonated pipe

 

test pipe means there's no cats, so your car will smell like gas when you drive... and is loud and raspy...

 

Gotcha, I'm looking for the clean rumble (Ferarri sounding exhaust), so HFC's would be the way to go?

 

HKS exhaust gives a nice exotic sound, HFC you may have more concerns when it comes to engine matienance and having stuff covered under warranty. HFC is a dealers eyes is a big no no. Some are cooler than others but as a whole they prefer a muffler or cat back system to HFC anyday.

 

To acheive that exotic car sound, the HKS is the only way to go exhaust wise. The sound is one of a kind. Adding the HFC's will offer you plenty of performance and the sound that you are sought after.

 

But dealerships are cool if you run straight pipes?

 

i think straight pipes (aka test pipes) and illegal in all states

 

Test pipes are illegal in all 50 states, HFCs are LEGAL in all 49 states except Cali.

 

In all honestly, dealerships dont really care what you have done to the car. Its all covered under the Magnuson Moss Act. The only things they dislike are motor internals forced induction.

 

Awesome, thanks for the advice. I'm also looking for good gains. I had Borla on my WRX and it sounded beautiful (deep, throaty, muscle car-esque, but not raspy). Seeing the gains that Borla has for the g37, I'm enticed but concerned about the sound. I've checked the sounds clips but I don't feel like I get an accurate representation of how it sounds in person.

 

I don't mind the illegality of either, I was running straight pipes with a resonator on my WRX and never got pulled over for noise violation. I just want to know which will sound best and perform best.