Hey guys,

So I installed the spacer and HFCs a day apart from each other (MD first) this week. Only prior mod on this car is a Stillen intake and Z tube.

The spacer took me 45 minutes tops and was very cut n dry. Upon start up there was no difference in noise. Cruising around felt almost exactly the same as before but with a little extra pep (placebo?). Pulling hard felt pretty normal as well. All in all not much difference.

I don't have jackstands so I got the HFCs professionally installed for $100. Upon start up it sounded normal but when I revved it, it sounded more throaty with a nice mild gurgle. Driving around, I just couldn't get enough of the resonances. They're everywhere! It sounded so good all through the rev range. I would say 20% louder on average. It's about 35% louder around 2.5k. She sounds gorgeous. The car feels much less restricted. I'm very happy with these.

I'll be getting the Osiris tune next week at Z Car Garage in San Jose. Any ideas what kind of power I'll be making at the wheels (Dynojet)?

Hope this was informative. Any input would be great!

 

Since the only changes you made to the exhaust system were replacing the OE cats with HFCs you're over powering the OE system, it wasn't designed for that kinda volume and you probably have rasp above 3K rpm. I would get an exhaust system before you get the tune so you get full benefit which should be plus 25+WHP and 19 ft lbs torque gains. That you'll feel!
Gary

 

Luckily I have no rasp. I've thought about for a while and decided to not to do an aftermarket set up. I did this instead because I love the sound of our stock exhaust.

 

What kind of HFCs did you get?

 

Stillens. Ironically Stillen wouldn't wouldn't sell them to me because I live in cali (they are located in cali...). So I bought them from the nismo shop instead!

 

Do you know why they didn't sell them to you? And if you don't mind me asking how much did you get them for?

Finally did you ever dyno your car? If so what numbers did you see?

 

Probably because theyre not legal in CA. Stillen is located in CA. Go figure.

Anyway here's a write up I did when I dynoed it:
https://g35driver.com/forums/tuner-d...ar-garage.html

 

Correct me on anythignn wrong: High flow cats give no CEL, Test pipes CEL?

 

If Stillen wants to stay in business he won't sell HFCs since by CARB standards they're not legal in CA. You can buy HFCs from our Marketplace since our vendors aren't the manufacture. I bought my last set from my tuner and he installed them. An increase of 14 WHP isn't what I expected after your tune, I got close to double that and 18 ft lbs torque. Some members get even better results than I did due to later models...Gary

 

^U missed the reason the thread was bumped

 

Even if it did throw a code the tuner could clear it real time with the software. So with respect to the question it shouldn't matter.

 

Not always true. Some CEL's will show up intermittently with HFC's, but it's less often than test pipes. Some test pipes won't throw CEL's if you have anti-foulers installed. You can tune them out, but may or may not pass readiness check if they just clear the codes.

 

Coincidently I've had them on for about 3 weeks and got the code yesterday. Reset it, came right back. Will try the foulers.

But..When the clear the code with the scan tool is that an ecu reset? If not I've never reset the ecu.

 

hi, I was just wondering how your stillen's are performing....everybody keeps telling me not to get them use y-pipe and middy from the coupe and it would sound and perform better than the stillen. im currently in the market to upgrade my entire exhaust system and advice would be great.