2.5" exhaust on stock ACR

kc2005ptgt · Post by **kc2005ptgt** » Mon Jun 05, 2006 9:42 pm

Ok, I think the exhaust has a flex pipe at the end of the cat on the stock system on my car (stop me if I am wrong) and I assume that is a 2.25" ID and goes into the exhaust piping and resonator (which is also 2.25") out to the muffler - am I wrong?

Ok, if I am right so far, let me ask a hypothetical question - what if I replace the entire exhaust piping from cat to the muffler with 2.5" exhaust piping/no resonator? and change the flex pipe to a 2.5" - would this be bad? Would there be gains?

I am also wondering what the inside diameter of the end of the header (do not know technicale name of it, sorry)? The part that connects to the cat? 2.25" also?

UMKCNeon04 · Post by **UMKCNeon04** » Mon Jun 05, 2006 10:16 pm

i installed a 2.5" on my sxt and love it. there was no flexpipe on mine but acr might be different. and i have no idea what my mag header pipe diameter is.

tamadrumr88 · Post by **tamadrumr88** » Mon Jun 05, 2006 10:37 pm

on a magnum header the primaries are 1-3/8" leading to a rough ~2" collector. the cat also crimps down to 2" when it bends back up to the rest of the exhaust

i vote for just getting a 2.25" system with a 31" glasspack

louie told me he was happiest with this combo (as far as sound goes).... stock magnum header/cat.... trubendz 2.5" pre-fabbed piping all the way back to his stock r/t muffler

TNK · Post by **TNK** » Mon Jun 05, 2006 11:55 pm

i thoguht raul-01 bought your car dude?

dblsg · Post by **dblsg** » Tue Jun 06, 2006 12:41 am

i thought that with 2.5 you would loose some bottom end power...

tamadrumr88 · Post by **tamadrumr88** » Tue Jun 06, 2006 8:13 am

dblsg wrote:i thought that with 2.5 you would loose some bottom end power...

if youre not running a longtube with a 2.5" merge collector you will

theres no point in putting a 2.5" exhaust on your car when it has several ~2" restrictions prior to that

kc2005ptgt · Post by **kc2005ptgt** » Tue Jun 06, 2006 11:12 am

I thought so - why in the world did they make the merge collector 2"?? thats retarded... I was just wondering if I could knock out the exhaust part prior to putting in a header... or if it would show good results with just the stock header and new piping.

tamadrumr88 wrote:louie told me he was happiest with this combo (as far as sound goes).... stock magnum header/cat.... trubendz 2.5" pre-fabbed piping all the way back to his stock r/t muffler

<< which is what I wanted to do.

I thought you just said this would cause a loss? and is not good? I guess if I was just looking for sound, it would be ok, but I do not want a loss of power. Where the heck is louie?? Haven't seen him 'round for a while. Hell, I can get the piping all done for inexpensive, wonder if I shuold just do it...

tamadrumr88 · Post by **tamadrumr88** » Tue Jun 06, 2006 11:36 am

kc2002acr wrote:I thought so - why in the world did they make the merge collector 2"?? thats retarded... I was just wondering if I could knock out the exhaust part prior to putting in a header... or if it would show good results with just the stock header and new piping.

I thought you just said this would cause a loss? and is not good? I guess if I was just looking for sound, it would be ok, but I do not want a loss of power. Where the heck is louie?? Haven't seen him 'round for a while. Hell, I can get the piping all done for inexpensive, wonder if I shuold just do it...

the COLLECTOR is 2", it is of a 'dump' design... not merge... it has a very rough transition. a merge collector has a much smoother transition and the velocity of the exhaust gas is maintained which keeps your low and mid range intact. a dump design is a very rough transition and because of this the exhaust gases suffer from a very abrupt velocity change because of the difference in area inside the header itself. a merge collector is very expensive and thats why the factory doesnt use them. a good merge collector will run about $200-300 which doesnt include the price of the header itself.

louie bought an s2k so he rarely comes on anymore. his AIM name is NotUrTypicalOne if you need to contact him

heres my vote.... stay with your current exhaust piping, replace with the 2.25" 31" long glasspack (from jegs: $19.99). you can remove your muffler in the mean time and decide at that point if thats the sound you want..... otherwise get the stock resonator replaced with a straight pipe, and get the dynomax super turbo muffler (#17755). its the 2.25" cross-flow design just like your stock muffler and then you can get the tips done up to work with your bumper cutouts

Kevin_GP · Post by **Kevin_GP** » Tue Jun 06, 2006 12:47 pm

Umm, well I have a 2.5 inch truebendz exhaust without a resinator. The pipe on the end of the cat is 2.25, before that there are restrictions. My vote is 2.5 truebendz WITH a resonator, and then you can upgrade to a long tube later on. With the 2.5 inch exhaust on my basicly stock ACR I felt no lose in the lower in, a tiny gain in the top end. Exhaust improvments wont gain you much untill you get a long tube.

My 2.5 inch with a magnaflow sounded good NA, alittle raspy when it was cold. Now with a turbo it sounds just plain mean.

kc2005ptgt · Post by **kc2005ptgt** » Tue Jun 06, 2006 2:07 pm

Ok, this is some good advice - I am deleting the resonator today (a friend will do it for free) and replacing it with a straight pipe and I will see what I think of the sound.

Maybe in the future I will do the Dawn 2.5" custom exhaust setup. I like that idea. First, to the muffler shop!

dawm · Post by **dawm** » Fri Jun 09, 2006 10:43 am

the flex part of the stock setup is at the neck of the cat (where it meets the manifold) there is no flex anywhere else on the stock system.

the dynomax 2.5" kit for the 2nd gen has a flex right after the cat, but its 2.25" which is stupid.

the dynomax 2.5" kit for the 1st gen is 2.5" all the way back

the mixed 1g/2g dynomax kit is also 2.5" all the way back, and just requires you cut off 1 bend from the 1g portion for it to bolt right up.

kc2005ptgt · Post by **kc2005ptgt** » Fri Jun 09, 2006 12:13 pm

I marked your post as a watched topic so I could reference it later.

:):):)

So, the flex is before the cat at the exhaust manifold? Not after it?

phenomeneon21 · Post by **phenomeneon21** » Fri Jun 09, 2006 2:52 pm

the flex on the stock exhaust is a part of the cat, it's in between the collector and the cat itself I think...I'd have to go look at mine again.

tamadrumr88 · Post by **tamadrumr88** » Fri Jun 09, 2006 3:32 pm

its a ball and socket joint which allows for some movement

kc2005ptgt · Post by **kc2005ptgt** » Fri Jun 09, 2006 8:36 pm

Ok, maybe stoopid, but I wonder if I were to replace at the collector instead of a "flex pipe" that is there attached to the cat, maybe do 2.5" flex and high flow cat 2.5" in and out, then a 2.5" exhaust all the way back to the stock muffler if it would do anything? If anything, it would just set me up for when I get a new muffler and LT header. the only thing I am worried about would be what if I lost power? I hate all this guessing, I wish I had money to just to some dyno pulls and test it all out. Dammit.

01rtgurl · Post by **01rtgurl** » Fri Jun 09, 2006 10:29 pm

kc2002acr wrote: I am also wondering what the inside diameter of the end of the header (do not know technicale name of it, sorry)? The part that connects to the cat? 2.25" also?

here is my stock mag header with calipers

: http://01rtgurl.irritates.us/gallery/Ra ... s/DSC02538

oh and

dawm wrote:the flex part of the stock setup is at the neck of the cat (where it meets the manifold) there is no flex anywhere else on the stock system.

http://01rtgurl.irritates.us/gallery/Ra ... s/DSC02506
http://01rtgurl.irritates.us/gallery/Ra ... s/DSC02505
hope that helps!

kc2005ptgt · Post by **kc2005ptgt** » Sat Jun 10, 2006 12:15 am

that says that the collector is almost 2.8 inches ID?? WOW

Mind is now churning... Ok, cool.. thanks Gurl! You rock nonstop!

2GN.ORG

2.5" exhaust on stock ACR

2.5" exhaust on stock ACR

Re: 2.5" exhaust on stock ACR