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Discussion Starter · #1 ·
I have a BCNR33 GTR with GTRS's and plenty of supporting mods.

I'm looking to upgrade the exhaust. At the moment I have nismo front pipes which are 2 x 60mm into 75mm.

The rear section is a Trust MX 80mm system.

I have a set of HKS front pipes to put on which are 2 x 70mm into 80mm. I'm figuring that I need a cat back that is at least 90mm. But, I don't like cannon mufflers. What are my options? I'd also like to keep it as quiet as possible.
 

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You have to define big power first.

In general, according to tuning companies in Japan:

80mm bore exhaust: Good to 400PS
90mm bore exhaust: Over 600PS

In short, you can get away alot with 80mm, probably up to GT-SS (around 550ps), but once you get into the 600, 90mm is a must and you probably will have a hard time to find a quiet one.
 

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we've just done a R33 GTR with a RB26/30 with a straight through 100mm exhaust with a single 100mm in rear muffler, it is surprisingly quiet at idle, cruze and low boost acceleration.

We have also just finished a 615whp stock internal RB30 in a R33 GTS and it has a straight through 75mm exhaust with a 75mm in rear muffler so not so sure about the 400hp limit mentioned above for a 80mm exhaust. :confused:
 

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If that is the case, then now I got a question.

Nito with his R34 T04Z struggle to get more than 600 horsepower out of this HKS Kensai Exhaust (90mm bore), and as soon as he change to a HKS Ti Racing (102mm bore), he pick up 30 horsepower with the same map.

I bought this but I don't think it will flow what I need. It is a 76mm (3 inch) pipe into a 3 inch muffler. Straight pipe, and pure titanium (only 5.2kg!!!)



would you think this will flow the 650bhp flywheel figure that I am looking for? If it will I may consider putting it on the car. There is 88mm? straight pipe exhaust on the car right now. What will be the difference between a 88mm and a 75mm exhaust in term of performance? Will one boost faster and other provide more low end (off boost) torque?
 

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Nito's Kansai exhaust was an 80 pipe that transferred to 90 after the cat, that's why it was too restrictive for him.
 

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Bean: What do you think of the 75mm exhaust above to handle over 600PS? Possible or wishful thinking?

I really like that exhaust, but if it can't do the job then there is no point for it. At least for me. :bawling: Great for stage 1 GTR though.
 

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Go to kakimoto racing website and check out there GTR selection, Go for the 90mm bore with the regu 92/96 tags (NOT N1s). However, you can't seem to get away from the 115mm tailpipes but then again 115 isn't much bigger than 90mm.

Be careful when checking catback flange size as the description doesn't always match size (you need to look at the diagram and check gasket part no. 80xxxx = 80mm & 90xxxx = 90mm).
 

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V1H said:
Go to kakimoto racing website and check out there GTR selection, Go for the 90mm bore with the regu 92/96 tags (NOT N1s). However, you can't seem to get away from the 115mm tailpipes but then again 115 isn't much bigger than 90mm.

Be careful when checking catback flange size as the description doesn't always match size (you need to look at the diagram and check gasket part no. 80xxxx = 80mm & 90xxxx = 90mm).
I also do like the kakimoto 1oz exhaust. looks the part. The only difference between the kakimoto and the rest of the lot to Reinhard is the price. Reinhard is ALOT cheaper. Titanium for the price of stainless steel almost.

However, the biggest size they do is 76mm, and that is where I am getting hurt by it. I am trying to get the exhaust to flow about 650 bhp in a single turbo GTR. it is running an external wastegate with a screamer pipe. And I read up that if you are using a screamer pipe, you can get away with using a smaller bore exhaust because some 1/4 of your exhaust gas will be vented straight out when you are on full boost and not into the exhaust system.

I really wanted a full titanium exhaust because the noise it make is so nice, weight saving is a bonus. Full Titanium exhaust sound alot different than a stainless steel system, and I am really hook on that sound. But if you want large bore, choice avaliable are custom made/Ganador/ARC at 90mm to 100mm bore size, and they all are around £2000 a piece. :chairshot

if i can get away using the 76mm and the ability to achieve my target of 650bhp, then I am happy. if there is no chance, then time to think of an alternative. I honestly thought there was no chance until R.I.P.S. NZ said that its possible. 650bhp at flywheel of couse.
 

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I'm not saying we couldn't have made more with a bigger exhaust but I can say we ran 129mph first time out with real bad 60ft, wheel spinning all the way down the 1/4, crossing the line all sideways in a 2wd R33 Gts. The last thing I was worried about changing was the 76mm exhaust! :p
 

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Hey ****

I think you should go custom Jerry Spec - Titanium JS front pipes 80x2 into 90x2 and into a single 4" system all the way, with a magic 4" cat.

I personally think you're at the 650hp mark atm, and really think your current exhaust is being maxed out. When we went old pac I could hear the damn thing popping and restricting your ass. Please upgrade :)
 

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Tommyk said:
Hey ****

I think you should go custom Jerry Spec - Titanium JS front pipes 80x2 into 90x2 and into a single 4" system all the way, with a magic 4" cat.
That sounds like an excellent spec....I'd go with that.
 

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Discussion Starter · #13 ·
Tommyk said:
Hey ****

I think you should go custom Jerry Spec - Titanium JS front pipes 80x2 into 90x2 and into a single 4" system all the way, with a magic 4" cat.

I personally think you're at the 650hp mark atm, and really think your current exhaust is being maxed out. When we went old pac I could hear the damn thing popping and restricting your ass. Please upgrade :)
Nah...not a fan of custom. And besides, the HKS dumps are only 60mm. I think 70mm into 85mm hks pipes and a 90-95mm cat back will do.

Yeah the exhaust is restricitve, sounds a bit like a vaccuum cleaner up high, but I don't want a cannnon.

This exhaust looks nice, but so exxy and mild steel.

http://www.kakimotoracing.co.jp/01-02-02_Kakimoto.R(web)/01-02-02_SO9001.html
 

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Anywhere in UK supply 102mm/4" straight sections and pre-bent sections (understand not many 4" mandrel benders about). Material wise, T304 (or other).?
I want to go custom at 4" (Downpipe, De-Cat, Straight Through, Rear Muffler Gutted with straight pipe through).
 

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nocturnal said:
But if you want large bore, choice avaliable are custom made/Ganador/ARC at 90mm to 100mm bore size, and they all are around £2000 a piece.
Yippee. I have a titanium ganador system. sounds awesome! :) :)

when mark from abbey saw it he really wanted to swap it for an hks beast and a load of money.
 
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