This is somewhat related to this topic.

I have been pulled over 2x for my exhaust [only in my hometown in West Covina].

Anyways, the 2 tickets I've gotten cost me much more than my custom exhaust, so I'm pretty much tired of this crap (its not because my exhaust is like a fartcan, its more of the bling from the rear that attracted the cops).

Without further adue, I currently have 2.5" piping and plan on cutting off my current muffler to accomodate either an s2000 muffler or ITR muffler for reasons of appearing stock from the rear. I realized the bottleneck effect. I would also like to mention that I will be doing a cutout before the cat just past the downpipe in the near future.

Should I scrap my plan and just redo the piping or will I be fine?

-NRG

 

Get the Hytech twin-loop muffler. It's very quiet and still flows as well as a cannister exhaust. You can just paint the muffler flat black for a stealth look.

 

I figure not to invest in a more expensive muffler like the twinloop since I will be doing a cutout, 3" downpipe to the ground (bad for the environment, but good for my car...yeah I know its bad, but I gotta do what I must do).

GSR guy, you do know what I'm talking about right? (It will be the next trend here on HT.com)

NRG

 

i'm runing 2.5" piping with the cheep as ss dc 2" colector

 

3"? Are you boosting? 3" is a bad idea for an NA setup.

As for a testpipe being better...there's virtually no gain. Dyno runs of test pipe vs high flow cat have shown a 1hp difference.

 

more harm than good?, it seems that everyone has their own good bad view of this set up so i guess there is nothing i can do but do it anyway and get my own results.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TheGSRGuy &raquo;</TD></TR><TR><TD CLASS="quote">You're probably doing more harm than good. Buy the header and cat now if you want, but don't install them until you get a 2.5" b-pipe/muffler.</TD></TR></TABLE>

 

This isn't an opinion -- I'm using basic physics to back this up. Even if you think about it logically, stepping down in size seems foolish.

If you want to do your own thing and place a bottleneck in your exhaust, by all means do it. It's your car and your horsepower. I'm done wasting my time on this thread.

 

I wouldn't say he is doing more bad than good, but that he will not get the full potential of the 2.5" collector header.

I went from a dc sports 4-1 2.25" collector to a JDM ITR 4-1 2.50" collector and from a CAI to a J's Racing replica SRI and I gained a significant amount of power across the entire power band. And that is dyno proven. 98ctr

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98ctr &raquo;</TD></TR><TR><TD CLASS="quote">I wouldn't say he is doing more bad than good, but that he will not get the full potential of the 2.5" collector header.

I went from a dc sports 4-1 2.25" collector to a JDM ITR 4-1 2.50" collector and from a CAI to a J's Racing replica SRI and I gained a significant amount of power across the entire power band. And that is dyno proven. 98ctr

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

It's good that you show your dyno bcuz if you just list your numbers than most people here will flame you for having a 1whp and 4wtq gain from your new mods.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Project X &raquo;</TD></TR><TR><TD CLASS="quote">

It's good that you show your dyno bcuz if you just list your numbers than most people here will flame you for having a 1whp and 4wtq gain from your new mods.
</TD></TR></TABLE>

Thats why peek horse power does not matter that much when you compare parts that you just swaped. As you can see from the chart I gained 10 whp in the mid range which is a verry significant. 98ctr

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98ctr &raquo;</TD></TR><TR><TD CLASS="quote">

Thats why peek horse power does not matter that much when you compare parts that you just swaped. As you can see from the chart I gained 10 whp in the mid range which is a verry significant. 98ctr</TD></TR></TABLE>

peak HP is just for braggin rights... most people have high HP cars but in their dyno sheets, the hp curve is everwhere, however you have a 'buff' dyno sheet my friend. BTW what setup are you runnin?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by NightRider-gsR &raquo;</TD></TR><TR><TD CLASS="quote">

peak HP is just for braggin rights... most people have high HP cars but in their dyno sheets, the hp curve is everwhere, however you have a 'buff' dyno sheet my friend. BTW what setup are you runnin?</TD></TR></TABLE>

b18c1, skunk2 IM, J's racing intake(fake),JDM ITR 4-1 header, 2.25" cat & cat back, ctr cams, hyamee cam gears, apex-i power fc. 98ctr

 

well im anxious to see how my motor gets out of it because it is a JDM Freak. I remember when i dynoed on and posted on here my results where like 2 or 3 hp from somone else who had like a full set up compare to my SRI and cat-back.

 

i have a dc jdm 4-1 with 2.5" collector,2.5" test pipe, tanabe racing medallion cat-back, the tanabe has a 2.36 mounting flange, then about 3 inches down the pipe, the pipe expands out to around 2.5"...so i have the 0.14 bottleneck for about 3 inches midway through my exhaust system.

but the jdm header made a BIG difference over my dc 4-2-1 ($25 plus shipping takes it)

 

i cant wait.

 

well I just got my JDM Header and high flow cat installed today. I must say my top end pulls like crazy now. Im dynoing the car next saturday so we will see if the $606 total that i spent of this whole project was worth it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Skunk2nR &raquo;</TD></TR><TR><TD CLASS="quote">The N1 is 60mm which is around 2.36"

2.5" header -&gt; 2.5" cat -&gt; 2.36" exhaust isn't so bad.

There are a number of people with this application, and they say it's running strong. </TD></TR></TABLE>

I'm one of those people.

About the 2.36 inch exhaust debate, a little backpressure is good and can help the vehicle put out a little more torque (search for more info). A lot of people with some of the craziest all motor setups are running a 2.5 inch collector and a 2.36 inch exhaust.

 

thats good to know

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TheGSRGuy &raquo;</TD></TR><TR><TD CLASS="quote">This isn't an opinion -- I'm using basic physics to back this up. Even if you think about it logically, stepping down in size seems foolish.

If you want to do your own thing and place a bottleneck in your exhaust, by all means do it. It's your car and your horsepower. I'm done wasting my time on this thread.</TD></TR></TABLE>

he's not technically stepping down in size. if he's running (which i think he is) stock exhaust manifold and stock cat with the 2.36" cat-back, if he goes with the 2.5" header and 2.5" cat, then technically, he's stepping up. he's just moving the bottleneck to the cat-back instead of leaving it at the exhaust manifold. he will get more flow (but not as much as if it was 2.5" straight through). all i can see here is improvements.

 

well its now the second day and all i can say is that there has been nothing but a improvement from the new set up. The bottle neck doesnt really exist and to know that im not at my full potential scares me cuse my car is pulling nice right now. I will wurry about a new exaust if a get pass emissions

 

Putting a narrower diameter B-pipe and muffler on is a lot like sticking a drinking straw on a firehose...a foolish idea.

I'm done wasting my time on this thread, do whatever you want.

 

Ok bye bye now

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TheGSRGuy &raquo;</TD></TR><TR><TD CLASS="quote">Putting a narrower diameter B-pipe and muffler on is a lot like sticking a drinking straw on a firehose...a foolish idea.

I'm done wasting my time on this thread, do whatever you want. </TD></TR></TABLE>

 

still better than stock...

 

straw = 3/16"
fire hose = 4"
difference = 3 13/16"

jdm itr header = 2.5"
cat back = 2.36"
difference = .14"

Now is it me or the difference between the two is like day to night.

YOUR POST

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TheGSRGuy &raquo;</TD></TR><TR><TD CLASS="quote">Putting a narrower diameter B-pipe and muffler on is a lot like sticking a drinking straw on a firehose...a foolish idea.

I'm done wasting my time on this thread, do whatever you want. </TD></TR></TABLE>

 

It is an overexaggeration meant to get my point across. If you're going to read into it that much, then that's precisely why you don't understand the physics behind the lost horsepower from this exhaust setup.