I want to upgrade my exhaust line this winter.

[Skym]

There's 2 types of exhaust you can fit to GTR.

1.) If you want more mid to top end hp for dragracing use, twin exhaust's (I think they are 3 inch each) from turbo's to rear of car. Kakimoto, Veilside are 2 tuners that make this type of exhaust.

2.) If you want more torque for racetrack use, twin front pipe into single 3.2"-3.5" catback exhaust. Mines, HKS, etc sell these types of exhaust.

But with twin front pipe into single pipe design, you need desired hp level to pick turbo size + dump pipe size and to work out the rest of exhaust size. You create what is called a megaphone effect (exhaust gets slightly bigger diameter wise as it reaches back of car), which helps to draw exhaust gas from turbo's. No more than 0.5 of a inch difference in diameter between sections (frontpipe, catback exhaust). Roughly 0.2 inch difference helps to keep exhaust velocity up and reduce turbulence that slows exhaust gas down.

As far as I know Apexi were the first tuner to use this megaphone idea in Japan.

For sound, as long as you have the factory 3 muffler setup on twin into single pipe design, sound levels should be at an acceptable level.

[Rapier46]

Exhaust made a huge difference on my rb20. Massive. Big dump pipe, down pipe, straight pipe exhaust. Wasn't even that loud. But it was like night and day. Them again I had a tuned ecu with a little higher boost.

[Skym]

Should be quieter when you run an equal length runner exhaust manifold.

[cobrAA]

And just to make sure the garage don't fool me.

How much should I expect to pay for all those mods?

[Skym]

Varies depending on material used to makes exhaust (titanium, stainless steel, mild steel) and where you buy it. Mild steel, around 1K with 3x mufflers. The rear muffler cost's the most (up to $500), so that's where the difference will be between cheap, expensive custom exhaust's.

But can find Japanese cat back exhaust's second hand, which is cheaper. Just need to be checked over for rust (mild steel), damage.

I run a 3" inlet Hayame exhaust on rear of my car with RB20DET -

http://www.phantasmusa.com/hay101008.html

[Rapier46]

my GTR with stright pipe, stock dump pipes, no cat, solid downpipe 3 inch entire way except small dump pipes:

http://www.youtube.com/watch?v=Lkx6gW1C7Cc

insanely loud in real life.

http://www.youtube.com/watch?v=dJHal4TjCuU

Tomei dump pipes, stock catback, no cat, solid downpipe. 3 inch all the way.

Ill throw up a vid of my rb20 also, man it was so smooth sounding, no crackling or gayness. i had 3.5 inch exhaust on it, to a 5 inch inside diametes muffles. still have it actually...might see how it sounds on the gtr.

[cobrAA]

Love britney haha!

[cobrAA]

Guys.. I need, at least, one thing to remain legal: Exhaust.

1. OEM stock exhaust cat-back
2. XL turbo catback with a ''S'' design ( not straight-pipe).

IMO, I'm better to go with the OEM because it's oem and working,straight-pipe so better sound and performance than a Turbo cat-back. Am-I right on this ?

Catalyser:

I saw a SARD control torque valve,is this thing working? Quebec might start doing emission test in a near futur, so I'm not so-sure if it's worth swapping this part. I mean, if it cost 300$ and I only gain 5 hp and can't pass the emission test, I'm sure I can make better investment.

Front pipe:

I would be surprise to learn that Nissan didn't make their pipe like it was suppose to be made ( with less bend possible). Can I really benefit of one more added inch to the diameter of the pipe ? It might also look better and be more weight less but I don't really care about those thing( it's under the car!)

Turbo Outlet pipe:

This upgrade look more important and seems to make more logic to me than the rest of the parts. Right? Quicker turbo spool is always nice and A/F sensor are already there.

[DrMango]

I still stand by that you won't see a 60hp jump without upping the boost. I'm talking just whatever boost you gain from the exaust alone. I know it wont be no 60whp. Even if someone says its a 40whp gain that isnt 60whp...

Kyle

[cobrAA]

I still stand by that you won't see a 60hp jump without upping the boost. I'm talking just whatever boost you gain from the exaust alone. I know it wont be no 60whp. Even if someone says its a 40whp gain that isnt 60whp...

Kyle

My boost is set to 13psi.

[DarkCaporaL]

Keep a good cat you can swap out for emissions and your gold.

If you dont want to be bothered, keep an empty cat on your car instead of bypass valves. Less noticeable.

[Skym]

DrMango, I would think 60awhp is probably with a ECU retune (Mines ECU, etc) that they didn't know about.

Up to 40hp for ECU retune + 40hp exhaust = up to 80awhp gain for GTR.

Also GTR is restricted by boost restrictor. Remove that boost restrictor and should see up to around 1bar / 14.7psi.

CobraAA, emission's probably would be more ECU tune related. If lean out rich factory fuel maps, adjust ignition timing maps, should get better fuel economy, better emissions.

[cobrAA]

DrMango, I would think 60awhp is probably with a ECU retune (Mines ECU, etc) that they didn't know about.

Up to 40hp for ECU retune + 40hp exhaust = up to 80awhp gain for GTR.

Also GTR is restricted by boost restrictor. Remove that boost restrictor and should see up to around 1bar / 14.7psi.

CobraAA, emission's probably would be more ECU tune related. If lean out rich factory fuel maps, adjust ignition timing maps, should get better fuel economy, better emissions.

Thanks Skym for all those replies.

My ECU have been retuned by Almasi tuning this winter, I will remove the restrictor this winter.

So, on top of all the mods I named previously, which one should be worth it in your opinion ?

[DJ]

Keep a good cat you can swap out for emissions and your gold.

If you dont want to be bothered, keep an empty cat on your car instead of bypass valves. Less noticeable.

Yes you can do that aswell,if you want I have a gutted cat,looks stock!

[DrMango]

DrMango, I would think 60awhp is probably with a ECU retune (Mines ECU, etc) that they didn't know about.

Up to 40hp for ECU retune + 40hp exhaust = up to 80awhp gain for GTR.

Also GTR is restricted by boost restrictor. Remove that boost restrictor and should see up to around 1bar / 14.7psi.

CobraAA, emission's probably would be more ECU tune related. If lean out rich factory fuel maps, adjust ignition timing maps, should get better fuel economy, better emissions.

Man now your adding removal of the boost restrictor and a retune to get there. No one said anything about doing all that to attain the 60 whp gain. It was said that if he installed a valve on his exaust and dumped his exaust there then he would then gain 60 whp. No one told him that he would need a tune for that hp. No one said that he would need to up the boost. We are assuming that HP would come from the boost he would gain from dumping out the valve right at his DP. The question was would he gain 60 hp from the open valve. NO he will not.

when the valve was open, he got an extra 60whp. Big gain there.

That is the misleading quote I'm talking about. I was just trying to let him know not to expect a 60 whp jump from opening this valve. We are not talking about any other factors here. I'm not trying to be a **** but your reading into this misleading info too much.
And If we want to get literal here. He did say WHP which means something more like 70-75 Hp at the crank. So now can we realistically see a 70-75 crank Hp jump from the valve being opened on a dyno, with no other factors?

This RB26 that makes a claimed 280-300 hp would now make an astounding 355-370~ Hp at the crank just from an exaust valve being open? There are no side factors here. If he meant that 60whp gain would be attained with a retune and more boost then when was he going to mention that? After his customer was mad for paying all this money expecting 60whp gains and he sees a 30 whp gain? Then he tells cobra that he should assume he meant with a retune and more boost? That stuff costs money too..
Kyle