Well with all the recent talk about header/exhaust set ups, I am second guessing my plans. I have a DC JDM 4-1 (not on the car yet), and was planning on ordering a carsound cat from IPS on wednsday. my intentions at first was to get the header and the cat put on, with 2.5" custom piping all the way to the stock ITR muffler. Do you guys think this would be a wise but temporory setup. I tried searching for it but couldn't find any usefull info. Thanks in advance to all.

thanks
-Arno

 

If you plan on running a 2.5" B-pipe, I would definately lose the stock ITR muffler.

 

ITR cat-back system is not that restrictive as you may think. On a stock cammed ITR, it's better than paying $300+ for a new cat-back system, IMO.

If it means any to you, skeptics, a friend's TodaB's + vafc + cam gear + stock compression gained only ~3hp/3tq running open header (when tuned) vs. testpipe + stock cat-back system. You tell me... is $300+ worth ~3hp/3tq? You be the judge.


[Modified by Cosworth, 10:31 PM 2/26/2002]

 

Ya I am definitely going to run 2.5" piping. Thanks for the response...any other opinions/comments..thanks

 

fawk... double post.


[Modified by Cosworth, 10:26 PM 2/26/2002]

 

I just had a discussion with SMSP about this. You'd be running 2.5" all the way to a muffler where there would be an abrumpt halt in exhaut flow because you go into 2-1/16" piping.

If you're going 2.5" all the way back get a new muffler too.

But, what can I say? I'm gonna be going from 2.5" Carsound Cat to a 2.36" ITR exhaust.. not as bad but, meh.

 

I think thats what I should do to get some pointers..thanks

 

*shrug*

Well..... I estimated a while ago that the ROI for allmotor is $100/whp... So that's about right.

Although, I think something more realistic is ~$500 for an off-the-shelf catback..... ~$300 for custom 2.5" piping is a much better alternative.....

 

If its smart to go with another muffler what should i got with....
The reason I even considered doing this is because of the great deal I got on the header. If i use the stock ITR muffler, the whole job, including header, carsound cat, and piping, will run no more than $400.

 

Here is a tiny bit of info for you. I currently have the DC JDM 4-1 header and a carsound cat from IPS mated to the stock b-pipe and exhaust. I will tell you that you can definitely feel the difference. No doubt about it!! I am going to leave it that way for a while as I do not want to be bothered with a noisy exhaust like the N1s. I would say just try the header and cat out and see how you like it. Then you can search around until you find the best exhaust/bpipe combo. Looking at the Dyno results form the great header test showed a larger exhaust only gained a small amount.

 

.....something with 70mm inlet or bigger. apex universal n1 or dunk comes in 80mm inlet for just the muffler.

 

Seeing as only the stock header ran with the stock exhaust, I think that only gaining 2-3 hp from an exhaust with a stock header shows how restrictive the stock USDM header really is.

 

ahhhh mannnn...im getting a lot of mixed results...

so at the end is it worth upgrading to bigger piping, and after market muffler or should i leave the stock b-pipe and muffler on???....

Thanks a lot for helping me out guys, i appreciate it,


[Modified by 98itR484, 7:27 AM 2/27/2002]

 

anybody else run this same set up????how did you guys like it??? Any info positive or negative at this point will be greatly appreciated

Thanks guys for all the help...(and sorry for all the stupid questions)

 

I would wait until you save up enough money and get everything all at once!! It is totally waste of money to get a tempory set up. Just leave it stock until you can do it all at once.

I would suggest any JDM header that have 2.5" collector, a 2.5" cat/testpipe, and Kakimoto R 70mm cat back exhaust. With this set up, you will have a true 2.5" ID all the way from the header to the muffler. Also, depend on the material of the cat/testpipe, you could have a fully stainless steel system!!

 

Ok first think about what you would like your final results to be. Do you really need huge dia exhuast sys or will it just be loud and you can loss HP if your not using the larger dia piping.

In Japan normally dia is 60mm (2.36in) or 60.5mm (2.38in)
2.5inch dia custom exhaust your talking about is 63.5mm but normally you will not find this in Japan or Europe unless it's custom done job.

Also you might also consider 70mm-80mm is sizing for FI cars in Japan not NA cars unless there making really high # Hp figures.

70mm exhaust sys is what you see on Skylines and Evos and WRX's in japan most often.

70mm (2.75in)
80mm (3.15in)

 

Im looking for some decent power..im not trying to go all out...I may slap on some cam gears, and a VAFC in the next month. but thats about as far as im going to go unless i come up on some money...

I dont want a big muffler, making a loud noise. I want to keep my stock muffler on. I am also being told that Dave at SMSP can provide an adapter to use on the carsound cat to weld the cat to the stock b-pipe. If i can use that, it will eliminate the 2.5" piping to the muffler. I know its going to cause a bottleneck.

 

Well if thats about all your going to do to your car then 60-60.5mm setups throughout will do you fine.

 

The Kakimoto R is 70mm OD, and its ID is very close to 2.5".

Isn't that what everyone with bigger cams and JDM header are looking for, a true 2.5" ID exhaust system to go with the 2.5" header and cat/test pipe? So I guess the 70mm piping is not only for Turbo car.

 

But why a 2.5" ID exhaust if your header is 2.5" OD?

 

Hytech from header to muffler. Just my 2cents

 

These stock exhaust wasn't used on any of the 2-1/2" headers for a comparo so we don't know what effect the 2-1/2" exhaust really had.