Hey guys, so I've been trying to fall in love with the stock GT4 sound and it just doesn't do it for me. Whether out on track at WOT or downshifting, the bassy tone and buzzsaw sound of the dual 3 cylinder is not what I had equated to a crisp, higher pitched wail from a flat 6. It's not a bad sound per say, but not as satisfying. I fought HARD to try and not do any exhaust modifications as I go to several track days and autoX events that all impose dB restrictions (and the stock system passes them all). However, I've discovered how much sound matters to my enjoyment of the car that I want to do something about this.

Initially looked into getting OAPs, but it just amplifies the same stock sound and louder noise is not necessarily what I'm after (once again due to dB level restrictions). The tone of the JCR system seems to be the best, followed by Kline (which requires you to get their OAPs).

Questions:
1) For those of you who have JCR exhaust with factory OAPs, do you notice the tone difference inside the cabin? (In some of the videos I've watched, the cabin basically sounds the same as stock)
2) From the outside, is the JCR non-silenced exhaust perceivably louder than factory back box?
3) If you do any track days or autoX, have you been flagged for noise violation? If so, what was your dB?
4) I heard ppl c/o drone from 2-3k, but unsure how much it actually affects the drivability of the car - your thoughts?

I welcome any and all comments, even from those w/ just OAPs or Kline set up. Thank you

 

1) yes
2) yes

 

The difference outside the cabin is a lot bigger than inside. I only had the factory exhaust on my car for 1 day so I wish i had a better benchmark. But I would say the difference to sound inside is subtle. While the difference outside is night and day.

 

Reedy, do you still feel like you can hear the exhaust as you’re driving or does the induction noise pretty much drown it out and it sounds stock from the inside?

 

Inside the cabin it's mostly induction noise. I need to ride along with a friends stock exhaust back to back to really tell as it's been 3 years with the JCR but I really don't think it does that much inside the cabin.

I do think that at the end of the day, the JCR exhaust does more for spectators than it does for the driver. I do get a LOT of complements at track day.

 

Yeah, JCR (and JCR+oap) had tons of people complimenting my car’s sound.

After adding Soul resonated OAP, it was a bit louder inside the car too for me. What was interesting was that inside the car , under maintenance throttle only, the car actually got a little quieter.

but … I removed my JCR box recently. It was just too loud 2-3k rpm in the car for me. Might be fine for you though!

JCR by far is best sounding option for our cars IMO

 

Thanks for the great info! Did the exhaust trigger any noise violation on track?

When you say it was too loud at 2-3k, are you talking about after you had gotten the Soul OAP or with stock OPFs? Or are you referring to the drone that some ppl describe around this rpm?

 

Yeah, sometimes I had to run the JCR bolt on silencers. Laguna Seca has tough sound restrictions sometimes.

For me it was that 2-3k rpm resonance that really did it for me. It’s hard to avoid it on canyon drives , etc. it started to make my ears ring. It got louder with OAP , but it was still kinda loud with stock OAP.

I’m interested to try the Soul v2 exhaust. X-pipe sound but they claim their quiet valve state really cuts the resonance by a lot.

 

I don't know of anyone who has had trouble with just the JCR race pipe matched with stock OAP's, the ones that have trouble with track noise limits all have OAP's.

 

Ah okay. The more I look into the matter, the more confusing it gets. It appears drone is an issue with any exhaust system, particularly with JCR… then again ppl say Kline doesn’t drone as much, but I am not sure if the folks with Kline run on track with sound limitations (and if it violates it). I feel like trying to resolve this noise issue just opens up a plethora of other problems lol

 

Yeah, only had issues with track limits when I added the OAP's

 

Nobody thinks their exhaust drones until they experience a bathroom emergency when stuck in heavy traffic. You'll find out exactly what rev ranges to avoid in that case.

It's all about your tolerance for it, the drone from my JCR honestly is very, VERY minor, but it is dishonest to say there is none. I just don't put load on the engine between 2000-2300rpm. Anything above that is perfectly fine.

 

I have a BGTS 4.0 with JCR Non-silenced with everything else stock and no valve controllers. I feel this has improved my enjoyment of the car significantly.
Yes, I can absolutely feel the difference inside the cabin. I only care about what it sounds like from the cabin.

I recorded a couple of videos for someone who asked the same question. The sound was recorded from inside the cabin i.e. no microphones near exhaust. The microphones were literally in my ears i.e. what I heard is what you will hear.
Perhaps you'll find it helpful.

 

wow, thank you for that. That does sound amazing. What great roads you get to drive on as well

 

I run the Kline system and I would say it is maybe 20-25% louder than stock but the tone is 100x better than stock. I think you would have no problem passing sounds regs with the Kline, even more so if you get the 3 way CG valve controller that lets you lock the valves closed for when you need to pass a mic. JCR also sounds great, but I personally wanted the smooth GT3 tone, the extra power bump of removing the OAP, W/O being much louder than stock... JCR with OAP is LOUD. I bet with the rear section alone the volume level is probably close to what Kline sounds like- the video above reaffirms that for me but it is always hard to tell through videos. For me Kline is still the best overall system for a street car, but if I wanted loud, JCR is the way to go.