I want to upgrade my exhaust line this winter.

[cobrAA]

I spoke with my mechanician and he said he will remove my RS*R ExmaGT2 cat-back for the OEM GTR because I'm sick of the stupid police.

While he's there is there anything else he should swap/remove?
- Upgrading the line from 3 to 4 inch( does it really matter) ?
- A new catalyser?
- Downpipe
etc etc.

He also said that for 300$ he would install an electric control valve that once open, the gas wouldn't pass throught the OEM exhaust. This mean that I should still have the same performance as I had with the RS*R exhaust.

He also told me that a guy ran 400whp with that setup and when the valve was open, he got an extra 60whp. Big gain there.

[Zacho]

when the valve was open, he got an extra 60whp

Your mechanic is full of it by the sounds of it. I'm sorry, 60 whp from an open dump....no.

Those valves are pretty neat, and I know they work. But the cheaper versions are known to fail from heat, and leak at the flap when it's closed.

It's like this, just with an electronically controlled cutoff to open/close the split. It just makes it like an open DP.

[cobrAA]

thanks for clarification!

But I don't think he was lying. he's not that kind of guy. pretty respected in the montreal area.

[NismoS-tune]

Here you go. I had a stock GTR with no cat, no muffler and straight through, maybe made an extra 10hp IF that. Anyways, going from 3 inch to 4 inch will become slightly louder. If you're trying to lose attention, a cat and 2 mufflers is key That's what I did. Nismo FTW

[Harvey]

or the muffler like what I am selling http://forums.gtrcanada.com/showthread.php?t=50483

[DarkCaporaL]

Be aware that if you upgrade the piping of install a bypass valve, your exhaust is no longer OEM, and you can still be stopped for it.

Bypass valve would fall under this regulation:

91. ...Any repair on any of the components shall be such as to preserve the original characteristics.

Chances are nobody will see it unless you get caught using it on the streets, but with the upcoming mandatory inspections on all old vehicles in a year or two, you will have to swap out your exhaust in order to pass.

[cobrAA]

Be aware that if you upgrade the piping of install a bypass valve, your exhaust is no longer OEM, and you can still be stopped for it.

Bypass valve would fall under this regulation:


Chances are nobody will see it unless you get caught using it on the streets, but with the upcoming mandatory inspections on all old vehicles in a year or two, you will have to swap out your exhaust in order to pass.

Mandatory is another thing.. but I'm sure policeman wont see anything!

[JDMricer]

RBs really aren't that loud anyway, we just did a 3" downpipe to a 4" exhaust on my friends rb25, it only has a single resonator, no cat, no muffler, and we still consider it to be fairly quiet. My 26 has a nismo 3.5" after the downpipe and it is too quiet for me, I would just reconsider your driving style and maybe stop opening it up in places you shouldn't like between buildings where the exhaust echos. As for 60whp thats also a long shot, maybe he said 6whp. I once had a car with a cutout on it, and it was fun when you hit the switch the problem is they are so large and hang so low they usually have a short life span.

[cobrAA]

Remember guys, The guy with 400whp have a OEM STOCK GTR exhaust. Maybe this is why the difference was bigger than a good quality aftermarket exhaust.

I live in Montreal, inside the island. The day I got my ticket ( for exhaust), I saw the police behind me, I was driving at 2k rpm! As soon a police see you, they follow you ! Sometimes they arrest you to say sh*t, something you get a ticket, sometimes they just pass by you after 5 minutes.

You know in Québec, there's a mandatory for JDM car, I guess the police check us more than you guys in other province.

[Rapier46]

Big dump pipes, big downpipe, no cat, and stock catback is what i have for cruising. Not very loud with the stock catback. Still sounds great though. and i have a straight pipe too if i want some noise

[DrMango]

RBs really aren't that loud anyway.

RBs are pretty quiet overall but they can be loud. My friends RB20 is one of the loudest tuner cars I've ever heard and it has a muffler still. My car isn't half as loud as his car. In alberta there isn't much worry about being pulled over though..

As for 60 WHP gain. That isn't even remotely a possiblity. I mean 0% chance. It doesn't matter how OEM the car is, it isnt possible. 6 WHP gain is likely because thats about average for gains with a aftermarket straight through exaust. Maybe up to 10 or so but thats still no 60

I just want to make my point that if you want the cutout then get it for the good reasons, not because of what gains you hope of getting from what you were told. They are pretty neat and would make for a good sound. Buy the cut out because of that if at all

Kyle

[Skym]

18rwkw / 24rwhp is the hp gain you should be seeing on RB20DET with full exhaust.

GTR is different, usually see bigger hp gains with 76mm+ exhaust's. Especially on stock R34 GTR, which it's not hard to reach over 400hp on a boost up and get stock clutch to slip.

[DrMango]

I don't see there being a 30 hp gain with removing cat and resonator and a high flow muffler. There is no chance of a 60 hp gain super duper GTRRB26million or not

Kyle

[Skym]

The increase in hp comes from increase in boost level that leans out factory rich fuel mixture.

This R33 with RB25DET was able to increase hp by 28rwkw / 37.5rwhp from a full X-Force exhaust and still has a catylitic convertor (high flow) -

http://www.youtube.com/watch?v=qoGctn5o2Kg

But R34GTR is twin turbo and has a better stock FMIC, slightly bigger turbo's, so see around the same or bigger hp gains with bigger diameter exhaust's. R34GTR produces around 330hp in stock trim, so 400hp is not hard to achieve. Nismo use stock R34GTR turbo's for 400hp on S-tune R32GTR.

On RB20DET you don't see big hp gains from exhaust mods like you do on RB25DET, RB26DETT.

[cobrAA]

Thanks Skym for proving my point. You wrote about the diameter of the exhaust. Should I consider swapping my line for 3 inch to 4 inch? Should i change the downpipe, remove the catalic or change it for a high performance ?? I don't know all the upgrade you can do to a line but my budget is approx 1000$.

The valve is 300$. installation is around 300$. So, i have another 400$ to play with.

Oh by the way, I heard that to make those big number HP gain, I need to install the cutoff close to the dump pipe.