Let's say I were to get hfc, wouldn't I need to do something else for the O2 readings? I've been searching on the forum and some have said that a service light keeps on appearing after installing HFCs.

Not really looking into TP.

You shouldn't have issues with HFC's at all. To keep it easy, if you get an Invidia exhaust, why not get the HFC's too? The difference between two HFC's from reputable manufacturers is going to be academic. Just stick with good companies and stay away from knock off's

IF for whatever reason you get a CEL, these will solve your problems. I didn't buy the L bend ones particularly. I bought 4 3" ones and double stacked on each side so effectively 6" on each side. CEL went off and never came back. I'll be doing the same thing once my test pipes get here.

2X O2 Oxygen Sensor Extension Extender M18 x 1 5 Bung Test Pipe Angled 90 Degree | eBay

I was wondering if you can run a motordyne intake manifold with k&n intakes? Thanks in advanced.

Would love to hear a sound bite of this set up. Im thinking about test pipes, but im worried it would be too loud ( I already have the G3 and Stillen CBE).

O2 extenders help, but you can still throw a CEL with them. There really is no full proof way of eliminating CELs with TP or HFCs unless you get a UPREV tune and close the loop to those sensors.

Guy at parts shop told me about a part like this as well... sounds like a winner but I think a tune is actually the best route. I posted a start up and idle of my set up on my profile.

shouldnt be any reason you couldnt. bolts up and sits just like the stock manifold. ill let you know since i have one on the way and im using k&n but safe to assume every guy that has it on here probably has an aftermarket intake.

http://www.importtuner.com/powerpage...sport_package/

Your welcome and I'm sure your capable of using the internet a little bit better! ;)

Ss firehawk: I'm close to getting a good deal on some stillen headers along with the nismo s-tuned exhaust. But I'm hesitant about getting the berk hfc due to the fact that it is gonna make the car a lot louder. That's why I was asking earlier what the difference was between the invidia and berk hfc because I wasn't too sure on which one to go with.

Chris: please let me know how the manifold turns out I am really interested in that mod. Also if you could let me know if there's a difference in the sound of the exhaust.

Thanks to everyone who has responded and helped me out, much appreciated.

It would be pointless to install headers and a nice free flowing exhaust without installing either TP's or HFC's. The OEM cats are the main choke point in our exhaust system.

I am pretty sure that anything you put in place of the Cat is going to make things louder. I would venture to say that a resonated pipe will muffle the sound a little bit more than a straight pipe. Depending on how many resonators you have to go through before you exit the exhaust will make the sound louder or not.... They act more as sound tuning rather than muffling though. A straight pipe is going to be loud combined with an open CatBack either way. I would get the HFC first and just try it with your stock (or look on youtube for different soundbites of different setups). I was just going to put my test pipes on with the stock exhaust at first but then the greddy fell in my lap. My car is loud as hell and there is no nice way to say that. I think a test pipe or HFC with a stock system will give you a little boost in power. The ultimate goal for me is to let the car breathe. For someone else it might be about getting a good high RPM note vs. a low rev note (so when they open it up it roars and when they are cruising in town it doesnt). Guess it pretty much depends on what your goal for the exhaust is.

So which hfc has higher quality between invidia and berk?

Either is good. I still wouldn't waste my money getting the stillen headers installed but if you really want them on. You definitely won't get a big power boost with the OEM cats on but good gawd, with headers and exhaust it does sound sexy!. Right now until my test pipes come in, I'm running Momentum headers, 350z OEM cats, and CNT exhaust and it sounds AMAZING! Real nice smooth and crisp exhaust sound. ZERO rasp since the OEM cats keep it from rasping but as mentioned, it is a power bottle neck. I'll post a sound clip later of how my exhaust sounds for now. I'm kinda sad it won't sound this smooth after the test pipes come in lol.

I heard a sound clip of a 370 w/ k&ns, stillen ss headers, OEM cats, and nismo cbe and it had a lot of rasp. Not sure if hfc will help the sound or not. Don't know too much about how all that would work together.