OK, the 98 Spec-R has the 2.5" collecter on the exhaust manifold. I'm guessing the stock cat is also 2.5" as is the rest of the exhaust, but I never knew for sure. Anyone here know?

Also, does the factory B-pipe have the "neck down" where it bolts to the cat like the ITR B-pipe here, as well as my Tanabe exhaust, or is it 2.5" all the way?

 

Looking at the fact that the JDM aftermarket B-pipes have this bottleneck I think the stock JDM B-pipe must have it also......

 

Forgive me, but where are you located? The collector on my USDM manifold was definitely NOT 2.5", nor was the exhaust diameter. As for your second question, the USDM ITR does have the bottleneck located at the cat-bpipe connection...

For a solution to those hindering bottlenecks, contact Dave (SMSP).

 

I believe he's talking about the JDM having the 2-1/2" collector, not the USDM.

Yes, talk to Dave. He provided my bottleneck solution.

 

not once did he say USDM, if you read the title, it says OEM JDM

 

I am in North America. I was referring to the JDM 98 Spec-R with the 4-1 exhaust manifold. I was wondering if the JDM B-pipe has the bottleneck like the USDM one, and also what the diameter of the system is there.

Just curious.


[Modified by Mycroft Holmes, 1:00 PM 9/27/2001]

 

My mistake...sorry

 

USDM is metric, but rounds out to about 2-1/4 after the bottleneck. I think $45 for the adapter and it cost me $35 to weld in. Works great, only you can't easily go back to stock if you should need or choose to. I'm not sure, but I'm betting the JDM b-pipe is 2-1/4 with a taper to keep the transition smooth, which is exactly what the SMSP adapter does at what will end up being less $$$ than trying to get a hold of a JDM b-pipe.

 

JDM is the same size, No bottleneck, the JDM ITR Cat goes from the 2.5" on one end down to 2.25 at the end connecting to the B pipe Also the JDM B pipe is 5" longer than ours (same length as a GSRs)

 

Thank you for the replies!

I never intended to try to locate a JDM B-pipe, but I was curious about the bottleneck because I figure if it's on the JDM b-pipe it's there for a reason and thus would not bother altering my Tanabe G-Power's B-pipe. Since it isn't I think I'll get the adapter for mine. I take it that the adapter is a weld-on part that eliminates the bottleneck, huh?

So how do I get ahold of SMSP?


[Modified by Mycroft Holmes, 6:50 PM 9/27/2001]

 

I don't believe that David has posted a phone number yet, but the e-mail he's currently using is smsproducts@novacoxmail.com

Hope that helps

 

It does. Thanks!