I know that the stock exhaust is choking my car but I cant afford an exhaust right now, and Im probably going to be doing a custom setup from scratch. I was wondering if anyone has tried to remove all or some of the bottle necks in the stock exhaust and if it seemed to help? Ive never closely examined the stock exhaust to see what can/should be removed or "fixed", but I assume there has to be 1 or 2 areas that can be "fixed" with a couple cuts and welds of some new piping or flanges. I was thinking about dropping the exhaust and playing with it some this weekend and just want to see what you guys think. Im thinking maybe Ill hollow out the cat (carsound) and try to fix a bottle neck or two, and maybe throw on a straight through muffler similar to the SMSP design.

 

Dave @ SMSP may still have available a b-pipe fix kit that opens up the first bottleneck right after the cat (cut and weld need, he supplies the flange with a welded tubing section). The latter restriction right before the axle-back muffler section would be the other problem but I havent heard much in the way of a fix for it , other than doing something similar on your own.

 

thx for the info.

I know Im not gonna get the most power out of the car with the stock exhaust, but just looking to free things up a bit.

If anyone has a decent pic of the entire stock ITR exhaust I would appreciate it. I cant seem to find any in search, bunch of red Xs.


Modified by RTW DC2 at 2:17 PM 10/29/2003

 

splat removed the first bottle neck in the b-pipe

 

Does anyone have pics of each Bottleneck?

I'm off to the local Muffler shop in an hour but want to be sure of each point that needs to be enlarged.

Thanks

 

by looking at the b-pipe,one can totally tell where it actually is becoming smaller.

 

From an archived post:



Dave (SMSP) has a better b-pipe derestrictor thingy than the one pictured, but I can't find a photo of it right now.

 

Check this thread.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Bbasso &raquo;</TD></TR><TR><TD CLASS="quote">Does anyone have pics of each Bottleneck?

I'm off to the local Muffler shop in an hour but want to be sure of each point that needs to be enlarged.

Thanks </TD></TR></TABLE>

How much did they quote to fix all the places?

 

I'm still working on that, All the local shops I went to today (6) don't have the correct flange needed to make a bottle neck remover.

 

theres one near cat and one near where axle back connects.. although that one is a small resonator.. so in my opinion, restrictions are a) bottleneck near cat b) larger resonator right after bottleneck c) small resonator near the end. then d) stock muffler.

 

Rob, I heard a Midas out in Ramsey NJ does custom exhaust work, and even has mandrel bent piping. If you are up for the drive, take a shot, I think they are located on RT 17 in Ramsey, northbound. 30min from the city at most. I havent had a chance to check them out for myself though, yet. They were just referred to me.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 96dc2 &raquo;</TD></TR><TR><TD CLASS="quote">Check this thread.</TD></TR></TABLE>

This is what you need. Get it from SMSP.


Here are the specs of the stock ITR exhaust:
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SMSP &raquo;</TD></TR><TR><TD CLASS="quote">Stock ITR is 57mm OD (2-1/4") with multiple bottle necks. The worse being at the B pipe inlet which is 1-3/4" ID. The B pipe necks down to around 2" or 2-1/16" OD at the B pipe to Axle back joint and the muffler tubing is 54mm OD and then necks again to 52-53mm right before it enters the muffler.
</TD></TR></TABLE>

 

bottleneck this...bottleneck that...save your money for a real exhaust.

even with all the bottlenecks removed you still have the largest bottleneck...the muffler itself.

i've seen way too many ITR's with all new piping done and the stock muffler intact...lets just say it sounds unType-R like. it sounds like JUNK.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by visi0n &raquo;</TD></TR><TR><TD CLASS="quote">bottleneck this...bottleneck that...save your money for a real exhaust.

even with all the bottlenecks removed you still have the largest bottleneck...the muffler itself.

i've seen way too many ITR's with all new piping done and the stock muffler intact...lets just say it sounds unType-R like. it sounds like JUNK.</TD></TR></TABLE>

My car exhaust has bottle necks removed and other ITR owners ask what intake I have, and why it sounds so good and different... and it cost less than the third of a new exhaust.

 

http://www.autospeed.com/cms/A_1082/article.html

 

Interesting article, I never saw it before. Is the non-USDM exhaust set up the same as the US spec other than the header?

 

Taking out the second resonator takes away the farty sound. I ran it without the muffler before and after chopping off the 2nd resonator. It sounds a lot lower in tone than with the 2nd resonator.

That's all I can tell ya.

 

I did almost exactly what you want but little more

DC 4-1&gt; 2.5 test pipe &gt; stock ITR exhaust(removed 2 bottlenecks)

I had a 2.5 n1 cat back b4 this and it was to loud for daily driving . I threw on the modified ITR cat back, and it was great! I honestly can't tell with the *** dyno any loss of power. With the stock muffler low end better ,but lost very little up top but it is hardly noticable.

IMO this is the best setup for my because my car is my daily driver.

 

I removed the bottleneck right after the cat on my ITR catback. I replaced it with 2 1/4" stainless steel piping (I still have some 2.25" SS for sale if anyone wants it). I can't comment on the power because I went from an Apexi N1 to this, but I'm not disaponted. My ITR exhaust will be for sale in a week or two as well.

 

out of curiousity why did honda manufacture the bpipes with bottlenecks?

 

For AUDM, the theory is the bottleneck between header and cat is to slow exhaust gas a little to heat up the cat quicker. Overall, as with any car, it comes back to a compromise between performance, budget, emissions and noise.

 

i dunno...my friend, neighbor, and guy i goto school with have 200hp itr's...maybe even more power using stock mufflers with whole new piping and it sounds tin canny under 5k rpm. do i like it...hell no.

 

would this work.........?......

i'm planning on purchasing a 4-1 JDM header and i plan to use a test pipe and get rid of the first bottleneck.

so, instead of adding a test pipe, can i just get a 2.5 inch pipe with the proper 2.5 inch OD collector to attach to the header and just weld the other side to where the bottleneck was cut off ???? so basically the exhaust after the header will be one piece.
i know i'll have to add a bung for the O2 sensor.

does this sound feasible?

PS- does the ECU throw codes when the second O2 sensor is left without the cat?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TypeRuz &raquo;</TD></TR><TR><TD CLASS="quote">would this work.........?......

i'm planning on purchasing a 4-1 JDM header and i plan to use a test pipe and get rid of the first bottleneck.

so, instead of adding a test pipe, can i just get a 2.5 inch pipe with the proper 2.5 inch OD collector to attach to the header and just weld the other side to where the bottleneck was cut off ???? so basically the exhaust after the header will be one piece.
i know i'll have to add a bung for the O2 sensor.

does this sound feasible?

PS- does the ECU throw codes when the second O2 sensor is left without the cat?</TD></TR></TABLE>

It sounds feasible. How well it'll work will depend on the fabricator.

And to the second question ... what? Is left without what?

Without the cat, you'll have a check engine light even if you add the secondary o2 bung and sensor. You'll have a check engine light if you remove the secondary o2 sensor.