Nissan GT-R Forum banner
1 - 20 of 24 Posts

· Registered
Joined
·
409 Posts
Discussion Starter · #1 ·
I have Cobb catted midpipe and stock cat back.

How much louder would the in-cabin and exterior sound be if I added these downpipes?

I'm trying to keep the in-cabin sound increase during cruising and normal driving to a minimum.

Any info is greatly appreciated.

Jonathan
 

· Registered
Joined
·
693 Posts
I can't comment on how much louder because I did everything at once. All I can say is DO IT. You won't regret it. It sounds incredible and not obnoxious. I'm running AMS non catted dp's with a catted Cobb mid, stock cat back. Couldn't be happier with the sound. If its too loud afterwards, just dynomat the interior. I'm doing mine, but even had I left the exhaust stock I'd be doing it. These cars are noisy.
 

· Banned
Joined
·
840 Posts
I had everything done at once too. However, I did have my midpipe and exhaust changed later so I got to hear those changes so I have a basic idea of what each piece contributes to the overall sound.

It is louder, but it does sound great. At low RPMs (ie. crusuing and normal driving like you mentioned) it isn't much louder than stock. It definitely isn't too loud in the car under normal driving and I think I'm fairly sensitive to that kind of thing. When you floor it and the revs go up it is louder, but it's a good loud. It puts a smile on your face for sure.
 

· I'll eat you like a KitKat woo who
Joined
·
1,349 Posts
If you keep your stock exhaust, it's not going to be much louder. I have AMS catless DP, CBRD MP and stock exhaust. I bought a 90mm exhaust and it was to loud for my wife. I had to change back and its much quieter. You will like the sound of your combo for sure.
 

· Registered
Joined
·
746 Posts
sounds clips of this anyone?
 

· Registered
Joined
·
866 Posts
If you keep your stock exhaust, it's not going to be much louder. I have AMS catless DP, CBRD MP and stock exhaust. I bought a 90mm exhaust and it was to loud for my wife. I had to change back and its much quieter. You will like the sound of your combo for sure.
Did you notice a decrease in power when you went back to your stock exhaust?
 

· I'll eat you like a KitKat woo who
Joined
·
1,349 Posts
Yes, I definitely felt some loss. But that would be expected from a smaller diameter piping. Is a 2012 or 13 stock exhaust bigger in size to a 09-11 stock exhaust? Maybe this would help w/ the power loss and still be on the quieter side.
 

· <"))))><
Joined
·
3,641 Posts
Yes, I definitely felt some loss. But that would be expected from a smaller diameter piping. Is a 2012 or 13 stock exhaust bigger in size to a 09-11 stock exhaust? Maybe this would help w/ the power loss and still be on the quieter side.
I doubt this is actually true. It is amazing what volume can do to the 'ole butt dyno.
 

· Premium Member
Joined
·
12,306 Posts
The sounds increase really depends on the exhaust and Y-Pipe you run. The exhausts systems we usually suggest to people, don't result in much of an increase when going to AMS Catless downpipes. Other brands might have some more resonance to them.
 

· Registered
Joined
·
409 Posts
Discussion Starter · #12 ·
The sounds increase really depends on the exhaust and Y-Pipe you run. The exhausts systems we usually suggest to people, don't result in much of an increase when going to AMS Catless downpipes. Other brands might have some more resonance to them.
Cobb catted mid-pipe and OEM cat back.

What would you suggest as an eventual 90 mm cat back to keep sound increase to a minimum if I added the AMS downpipes?
 

· <"))))><
Joined
·
3,641 Posts
Sharif hooked me up with the 100+mm GTC Titan exhaust, all titanium, downpipe back. It is incredible and I think has less resonance that the stock catback but with a much better sound a WOT. I would strongly suggest this solution.
 

· Registered
Joined
·
2,864 Posts
Sharif hooked me up with the 100+mm GTC Titan exhaust, all titanium, downpipe back. It is incredible and I think has less resonance that the stock catback but with a much better sound a WOT. I would strongly suggest this solution.
Over 90mm I heard you need upgraded turbos, otherwise the diameter is too large and you lose either HP or tq.
The titanium downpipes I heard also get too hot due to being right after the turbos which is why they are usually made out of SS or Inconel, but this may not be true for all titaniums as their compositions vary.
Can you post a sound clip?
 

· Premium Member
Joined
·
12,306 Posts
Over 90mm I heard you need upgraded turbos, otherwise the diameter is too large and you lose either HP or tq.
The titanium downpipes I heard also get too hot due to being right after the turbos which is why they are usually made out of SS or Inconel, but this may not be true for all titaniums as their compositions vary.
Can you post a sound clip?
Turbochargers like less backpressure, not more. So a larger pipe will not result in less mid-range torque. On the contrary, when you reduce exhaust gas restriction, you will experience faster turbo spool up which means more mid range trq. You would be correct, however, in a naturally aspirated setup where you can definately go too big.
 

· Registered
Joined
·
406 Posts
If you install downpipes is it even possible to use the Cobb AP to revert back to the stock tune when taking the car into Nissan for say a 24 or 36 month POS? My understanding is that you can't run the stock tune with aftermarket downpipes. I want downpipes but that's my main concern.
 

· I'll eat you like a KitKat woo who
Joined
·
1,349 Posts
You can use aftermarket DP w/ out a Cobb. You will not get the full potential of your DPs. If you install catless DPs, you will eventually get a CEL. This will not harm your engine, it will just on your nerves. You can get your tuner to turn off CEL light w/ the Cobb.
 

· Registered
Joined
·
406 Posts
You can use aftermarket DP w/ out a Cobb. You will not get the full potential of your DPs. If you install catless DPs, you will eventually get a check engine light. This will not harm your engine, it will just on your nerves. I had to go to the dealer for some warranty work and I un-installed the Cobb w/ out any issues. P.s, it was a mod friendly dealer.
Are you saying that I can add catless downpipes to my 12 and still revert the tune back to stock before dropping the car off at Nissan for a 24 POS and having the stock tune with catless downpipes and full exhaust will not affect or overboost the car? If so, then I'll get some downpipes. Do you have downpipes?

This must be different for the 3 inch intakes I'm going to have installed because they are before the engine (I plan to remove the 3 inchers and replace the stock intakes when it goes into Nissan just to avoid issues - plus I was told that the stock tune is not good for use with 3 inch intakes installed because too much air).
 
1 - 20 of 24 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top