Nissan GT-R Forum banner
1 - 8 of 8 Posts

·
Registered
Joined
·
147 Posts
Discussion Starter · #1 ·
Can someone please let me know what the oem exhaust piping and exhaust tip diameter are, been searching online and can't get a number. Also what piping diameter should you go to with an aftermarket exhaust for good gains? I have a 90mm AAM midpipe right now and I'm looking at an aftermarket exahust but its only 3" piping (76mm) so wondering if thats the oem size and if it will be pointless/bottleneck wth my midpipe?
 

·
Registered
Joined
·
8,155 Posts
I had 3" catback and I can tell you it will not be a bottleneck on stock turbos. I ran 129 mph trap speed with 3" and 129 mph with 3.5". I have many documented runs (track times along with vbox) and average the trap speeds and there are no difference.
 

·
Registered
Joined
·
3,318 Posts
oem tip flange is 60mm
 

·
Registered
Joined
·
413 Posts
I had previously asked that same question and according to the info given to me by the people at Cobb Tuning, OEM pipe is 3 inch or 76mm.
 

·
Registered
Joined
·
147 Posts
Discussion Starter · #6 ·
yes I confirmed with several shops and the OEM piping diameter is 3" or 76mm. Cobb is also developing a 3" exahust for the GTR due out later this year. Seems like the GTR alraedy has an efficient exhaust and really the only benefit of going 3" aftermarket is for weight savings, looks, sound, but theres no perforamnce gains outright unless you go with bigger turbos in which case you may need to jump to 3.5" or something.
 

·
Registered
Joined
·
413 Posts
yes I confirmed with several shops and the OEM piping diameter is 3" or 76mm. Cobb is also developing a 3" exahust for the GTR due out later this year. Seems like the GTR alraedy has an efficient exhaust and really the only benefit of going 3" aftermarket is for weight savings, looks, sound, but theres no perforamnce gains outright unless you go with bigger turbos in which case you may need to jump to 3.5" or something.
I've been told exactly the same thing in the past as well. This is the first I've heard of the Cobb exhaust, though. I don't know why they would make a 3" exhaust when that's the OEM diameter. Their midpipe is 90mm (3.5") so you would think that they would make their cat-back the same diameter.
 

·
Premium Member
Joined
·
350 Posts
Hello, going off our exhaust comparison spreadsheet we made a while back, the OEM catback's intermediate (single) pipe is 66.5mm INSIDE DIAMETER. When it splits into two pipes before entering the mufflers, it is an oval shape and not round, so we would have to cut it apart to get inside diameter which we have not done. The exhaust tips are also a bit oval at 105mm x 111mm x4 tips. It weighs 36 pounds.

The stock Y-pipe weighs 30 pounds. The dual pipes coming from the downpipes are 64.9mm ID, and the single pipe that connects to the catback's intermediate pipe is 67mm ID.

Hopefully this helps answer your question precisely
Please let us know if you need any other help/advice!
 
1 - 8 of 8 Posts
Top