I've been debating on what to do for an exhaust set-up to compliment my new JDM DC 4-1 header and Carsound cat. I'm really leaning towards keeping the stock ITR exhaust(less noise/attention), but would like to remove as many restrictions as possible. I plan to start by using SMSP's 2 1/2" cat/b-pipe adaptor. David also mentioned I could have the resonator removed from the stock b-pipe and replaced with a straight 2 1/4" pipe. My question is...

Would this greatly increase the sound of the exhaust? Any other drawbacks to doing this? Would it be more cost effective to just order a new b-pipe or have one custom made?

David mentioned that he thought some people on this board may have done this and could provide me with some firsthand feedback.

Thanks for the help.

Chris

 

I don't think the resonator is the bottleneck. It's the flanges at the front and at the back that are restrictive.
Maybe SMSP is talking about the second resonator (the small one).
I think removing the first bottleneck is enough, because you are keeping the stock muffler.
The muffler also has 3 restrictions. That's one of the reasons that makes it quiet.




[Modified by EuroITR1689, 1:07 PM 1/30/2002]

 

yes

 

OK. I don't see what can be gained if he doesn't do anything with the muffler. He wants to keep his stock muffler, right?

 

I think he wants the option of changing it out in the future, so if he removes the B pipe bottle neck and the small resonator he'll have a true 2-1/4" B pipe and if he replaces the stock muffler in the future with a 2-1/4", 60mm or even 2-1/2" , he'll have a decent system. The stock muffler, with it's 2-1/16" OD inlet/outlet tubing needs to be replaced if you want to open the system up.

 

But will the new 57 mm flange fits on the stock 52 mm muffler flange? Sorry, I like to use the metric system....

 

The stock muffler flange is flared to accept the donut, so it's inlet is much larger than 52mm. I'm currently looking at pricing just a 2-1/2" B pipe with a 2 bolt flange that will bolt up to the stock muffler.

 

Hrmmmnesss

Will
-who would have to save more money

 

BTW. Did Honda put the second resonator there to reduce the wave energy (or something) of the exhaust gasses before it goes in the narrower pipe of the muffler? This reduces the backpressure, right?

 

Need a test mule?


Pat, who will be eagerly awaiting said b-pipe...

 

I can build it, but I'm not sure you guys want to pay the price of piecing one of these B pipes together. To copy the stock B pipe layout it would take 5 mandrel bends and a couple pieces of straight tubing. I have a stock ITR B pipe so I can build it from that.

SMSP - Who thinks stainless steel mandrel bends are expensive, fyi you can check out some prices on line at http://burnsstainless.com/304tubing/304tubing.html

 

Just get a TypeONE b-pipe

Removing the stock resonator won't benefit you much and the exhaust will sounds like chit.


[Modified by AJ PwR, 10:18 AM 1/30/2002]

 

That is an option but you'd still have to do something about the bottle neck in the B Pipe. The Type One 2-1/2" exhaust has an inlet of 2.15" at the B pipe flange, but cats built to bolt on to JDM headers have an outlet of 2.50" and even a 2-1/2" test pipe has an ID of 2.37". Therefore, you have about a 3/16" (.35" total) mismatch all the way around the B pipe flange when using a cat.

I don't think sound would be greatly effected by removing the little resonator, heck you could even just replace it with a true 2-1/4" one.


[Modified by SMSP, 11:07 AM 1/30/2002]

 

i think removing the resonator would make the exhaust louder and raspier but you may lose low end torque.

 

At the header test when we went from the stock manifold and exhaust with a 2-1/4" cat to the stock manifold and my 2-1/2" cat back exhaust there was about a 1 lb-ft torque loss from 3100-3400 but every place else up to 5000 rpm it was even and then picked up after that. So no real loss of power up to 5000 rpm even with a full 2-1/2" cat back system.

 

Here is my OE ITR B-pipe with resonator removed. Dave @ SMSP suggested this before he built the prototype 2.5" cat-back for me.

I had Toda cams during this time, but the noise was not that loud. It was a lot quieter than my roommate's N1 set-up. The 2.5" dia. x 3' long pipe cost like $35-40 total.

 

here ya go:

 

Did you have a muffler shop cut out the resonator and replace it with a straight pipe or was it more invovled than that.

 

What he said...

 

It was just that simple! Dave @ SMSP did supply me with a 2.50-2.25" reducer that we welded to the end of the straight pipe. This smoothed the transition into the OE pipe. I think Jason (darth vader) picked up a few whp when he installed this reducer on his Tanabe cat-back.

 

My ITR header collector is in a slightly different location (right-left) within the tunnel versus a standard JDM type header so we were able to use a straight piece of tubing versus the stock offset. Then we used a tapered cone to reduce down to the 2-1/4" B pipe. This system wasn't on the vehicle for long before RStoR went with the 2-1/2" adjustable B pipe. I don't recommend cutting the large resonator out of the system.

 

I have a stock ITR B-pipe, in a box ready to be shipped. You can chop that one up if you want..

 

There is some misunderstanding here. SMSP is refering to the small resonator, not the big one. I don't see the benefit of removing the big resonator. You only need to remove the flange....