Pro Circuit T-4 ... Any good?

I'm thinking of buying the T-4 for my bike and i've noticed that alot of you have the Yoshi pipe.. how does the T-4 compare?

What others are good?


PS.. Noise isn't a major problem. There are plenty of WR400/426 running around with YZF pipes on them here in Aussieland!


The Pro Circuit T-4 is as good an exhaust system as you can get. It doesn't make as much power at the very top of the power band as the full Yoshimura system but is real close. I have ran the T-4 exhaust and would recommend it if you don't mind the noise and they come forestry approved. I run the Yoshimura on my trail bike for various reasons but the T-4 is very good.

I have not seen anyone with a T4 system in my area. However I can say the Yoshi system does a very good job. I am also considering the cam&ignition kit offered. Did you get the Pics of my bike?

I'm leaning toward the T-4 because it looks really nice.. nice and slim!

I don't think i got your pictures Richard. :)

Did you sign in with a different name?


Yep Richard.. got your pic.

I wouldn't mind a bike trailer like that one you've got there.

Are there any articles comparing pipes?

The T-4 System is nice and it is plug and play set up. I have it and the stock jetting seems just fine but the bike is still to new to peg. The engine revs more freely and seems to have more pop. :)

The t-4 can be used with stock jetting? I thought a re jet was required.

Does anyone know if there are any articles published comparing different pipes for power and noise?

I'm thinking of getting the

T-4 too, but noise is a concern where I ride. Has anyone used a silencer or baffle with the T-4? It almost seems self-defeating to buy the exhaust and then put a silencer on it.

Here is the cheese abouth the T4,

my bike came with one,

it is an open pipe(no baffle)

the nice thing is that the header pipe has the same outside diam. as the stock, so if needed (state inspection) a stock muffler can be easily slipped back on.

It is loud in stock form (open), procircuit sells a "quiet core" for $30, after I purchased it, I found it still too loud, and it has a tin-can sound.

PC sells different size end caps to fine tune the muffler.

End caps can be very easily changed , so i've been experementing making diferent baffles for it. when I want quit, unscrew 3 bolts and slap the quiet(homemade) baffle in, and when i am trailering it to a cycle park, just remove the baffle and let it rip.


looks cool, light weight, forest approved, interchangabe caps or baffles, noticable power and quicker revs.

disadvantage: cost $, loud, no heat shield.

I just found a magazine with and article testing 7 different aftermarket pipes.

The Yoshimura came out on top and the second best was White Brothers "R" Series.

The T-4 was down the list a bit.

I'm now reconsidering my choice and i'll go for the White Bros. R-Series.

Good power gains and you don't need a header pipe so it's cheap horsepower! :)


The "R" series pipe that was tested by Dirt Rider Mag. Aug.2000 issue along with six other brands made 42.6 HP and the T-4 was 42.5 HP. The R" series was tested with the oversize header. The test on the Yoshimura was 43.5 HP @9500 RPM.

The "R" didn't get there until 9750. The T-4 got its power a little lower at 9250.

The magazine i'm looking at is Dirt Bike and in the tests, the Pro Circuit made 41.7 w/165 main jet and airbox lid off but the WB-R made 42.4 w/165 main and airbox lid off.

Not only that, it was better than the T-4 all the way from 4000 rpm till knock-off time!

If your article is different, can we swap?


The exhaust sytems from 2000 are way different from todays exhaust.

DRZ_downunder, what year and issue were you looking at?

Well, it says issue 3 on the cover but on the bottom of the 1st page of the article it says August 2000. The 2nd and 3rd pages it says July 2000 ???

The article is titled "Exhaleration Tests" -

"Better breathing makes a healthier DRZ"

has anyone tested the Big Gun system for the S? i'm already sold on this system for various reasons,but,just curious.

Now I am curious as to what the numbers would be on the newest line of exhausts. I know Yosh along with some other top brands have changed a lot about thier systems and most offer interchangeable parts. The system I bought is a 2000 RS-3 stainless full race. My buddy bought a stainless full race Yosh right before Christmas and it is a lot different from mine! After he puts it on, I will try it out for myself. I am at the point of putting my bike on a dyno to see what I got. It makes me feel good to know.

Has anybody read any recent articles on these exhausts? :):D

I can't find my issue of that magazine. Can someone tell me what it says about the White Brother's E-Series "S" bend? Please Please Please :)

In this magazine:

White Brothers E-Series w/165 main jet and airbox lid off : 40.9Hp

Looks to be a good mid range pipe.

Are there different models? S-Bend/Other?

They also have a E-Series Pro-Meg, which I believe is an upper rpm type performer. My dad has the S-bend, but it's too loud for him. So I got him the quiet insert for it for Christmas. He hasn't tried it yet though.

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