Upgrade from Dual ATR 2.5"?

MNwe4

Member
Is there anything to be gained in going from the dual 2.5" ATR to the dual 3" GN1 exhaust with the my following combo?
Stroker 109, 6265 turbo, 3" ATR external gate downpipe, and cutout/test pipe?

I know the total area of the dual 2.5" is larger than the 3" downpipe, so quick math says no, but there's lots of you guys with first hand experience out there. Took the cap off of the cutout and went for a rip tonight. It felt like it had more pep, but there's no numbers to prove it and the extra noise could have created a placebo effect. Always looking for quicker spool up...
 
My dyno comparo showed 4-5 RWHP gain with the 2.5" system doing an open vs closed dump.
The headers were the ATR 4 bolt with a GTQ70.
Pulls were back to back and repeated 3 times.
274" S2 thru a T400.
In your case, I'd not spend the money.
 
What is your air intake setup, & converter stall speed? Maybe go bigger & looser.. or a ball bearing turbo
 
I'm running low 10's through my dual ATR 2.5" exhaust into Pitbull muffs and don't plan on changing it out with the new motor , which should be mid 9 sec. Like Chuck said , save your money .
 
Is there anything to be gained in going from the dual 2.5" ATR to the dual 3" GN1 exhaust with the my following combo?
Stroker 109, 6265 turbo, 3" ATR external gate downpipe, and cutout/test pipe?

I know the total area of the dual 2.5" is larger than the 3" downpipe, so quick math says no, but there's lots of you guys with first hand experience out there. Took the cap off of the cutout and went for a rip tonight. It felt like it had more pep, but there's no numbers to prove it and the extra noise could have created a placebo effect. Always looking for quicker spool up...
Need to look at fuel usage or put the car on a draggy.
I will say this want to fast loose the weight and put a single shot on the car and dont go over the axle
 
These are some good replies. Thanks. I have lots of PL data through the exhaust and just one pull with tire spin on the 2-3 shift with cutout open from yesterday. Wow was it loud with the windows down. Best ET 10.70 @ 126. As mentioned primary goal is quicker spool up. Those pesky Hellcats (if on DRs) jump 2 cars on me from a roll and I have to reel them back in...

How much do you guys think the ATR 2.5" cat back system weighs? I thought I read long ago it was only 27 lbs. Wonder what the 3" GN1 weighs as well.

Other info: Loose NL converter from Husek, turbo is BB, RJC 4" MAF pipe, ATR front mount IC with 2.5" piping, 3" LT1 MAF is in up pipe as blow through, Champion AL heads, ported stock intake. Yes, other than stock style TA headers all of my piping post turbo is ATR from the early 2000's.
 
In regards to weight, my single 4" RJC was 24 pounds lighter than the 2.5 dual setup that was on my car and I know it wasn't ATR. If I were to stop it at the axle like MRSpool suggested it may save another 5 lbs. Im sure a single 3" is lighter.
Single.jpg
 
The art stuff is really really heavy.
Good real 304 stainless from back in the day.
But awefull for a diet.
The lighter car will always have an advantage
 
Sounds like the consensus is that I won't gain much from changing exhaust at my current power level and 3" downpipe. I will say the 2.5" ATR has a great mellow tone while cruising around. I might experiment with a 3" muffler directly off of the downpipe and have it come out under the passenger door just for fun if time ever permits. From the end of my downpipe to where the floor drops closer to the ground is about 35", so there's enough room there for a decent muffler and turn out with a rectangle or oval flange. I'd love to see pics if anyone has done this.
 
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