LT1-LT4 Modifications 1993-97 Gen II Small Block V8

True Duals vs. Cat Back...

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Old Oct 25, 2006 | 05:02 PM
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Default True Duals vs. Cat Back...

I'm looking into going to 3" true duals with Magna Flows or Edelbrock 304s with an X pipe and dumped at the axle to replace my Borla cat back run wide open...I'm looking for people who have done back to back track comparisons going from cat backs to true duals...dyno results are fine, too...

My exhaust is currently Kooks stepped 1 3/4-1 7/8 LTs, Kooks 3" off road Y, and Borla cat back...Anyone done a similar swap and have track results to help me decide if its a worthwhile swap? Thanks...

--Alan
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Old Oct 25, 2006 | 07:50 PM
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BBK shorty headers with Stock SS cat back :
274.5 HP / 306.4 TQ

Pacesetter Longtubes and TSP X-pipe (3" dumped in front of axle) :
282.1 HP / 319.7 TQ

Motor was stock SS with Hypertech programming. Probably not a big help at your level but, what the hell...
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Old Oct 26, 2006 | 12:42 PM
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Hey, thanks...a gain is a gain...Anyone else?

--Alan
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Old Oct 26, 2006 | 12:55 PM
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On a h/c/bolt on motor my guess would be around 10ishrwhp, sorry no numbers to prove it though.
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Old Oct 26, 2006 | 04:47 PM
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Alan,

After hearing of your car running so well and driving to the track, I will give you my honest oppinion on going from a Y-pipe to true duals.

If you want your car to remain enjoyable and "streetable" keep your setup. True duals are very loud and low.

I had a Y pipe with a flowmaster exhaust behind it and gained 33 rwhp by opening the cutouts right off my headers. I could drive the setup anywhere and the car was very streetable. In an attempt to get that hp gain all the time I went to a summit X pipe with bullit mufflers dumping at the axle.

While it gained plenty of hp (25-30) over my closed cutout y pipe setup, it is far less streetable. It is very loud and leaves me with maybe 3 inches of ground clearence. The car made a giant step into race car territory by swapping the exhaust.

Another thing to consider is that a chasis mounted torque arm will be tough to clear with true duals. My x pipe had to be extended and bent in all sorts of ways to get around the mount (part of why it is so low). If you are running one, it will make true duals interesting.

If you want an exhaust that won't have these problems you will likely pay a huge amount for a custom one.

I would put a cutout off your primaries and pull the catback out at the track for weight reduction. It would leave it streetable.
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Old Oct 26, 2006 | 05:16 PM
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I dd a heads/cam/bolt on car with true duals but mine is ran out the back so it is not near as loud as when it was dumped. Yes ground clearance sucks but I do have a 3 inch x pipe, I also have a chasis mounted torque arm and all it took was a little banging on the x pipe to make it all fit. So it is all just up to you if you want to deal with little bs that comes with the enjoyment of having true duals.

Also I'm trying to get a dd just not enough money right now lol
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Old Oct 26, 2006 | 05:17 PM
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BMR makes the upper panhard relocation bar also so that you can fit two bigger pipes over the axle... Could look into just routing to pipes with that out the back. Just a thought...
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Old Oct 26, 2006 | 05:17 PM
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Originally Posted by Tireburnin
Alan,

After hearing of your car running so well and driving to the track, I will give you my honest oppinion on going from a Y-pipe to true duals.

If you want your car to remain enjoyable and "streetable" keep your setup. True duals are very loud and low.

I had a Y pipe with a flowmaster exhaust behind it and gained 33 rwhp by opening the cutouts right off my headers. I could drive the setup anywhere and the car was very streetable. In an attempt to get that hp gain all the time I went to a summit X pipe with bullit mufflers dumping at the axle.

While it gained plenty of hp (25-30) over my closed cutout y pipe setup, it is far less streetable. It is very loud and leaves me with maybe 3 inches of ground clearence. The car made a giant step into race car territory by swapping the exhaust.

Another thing to consider is that a chasis mounted torque arm will be tough to clear with true duals. My x pipe had to be extended and bent in all sorts of ways to get around the mount (part of why it is so low). If you are running one, it will make true duals interesting.

If you want an exhaust that won't have these problems you will likely pay a huge amount for a custom one.

I would put a cutout off your primaries and pull the catback out at the track for weight reduction. It would leave it streetable.
Thanks...yeah I'm still on the fence about it...The guy that does the duals locally does everything custom and gives excellent ground clearance by actually putting the X between the Spohn TA mount and the body...The lowest points are the mufflers which are either 4"x9" (MagnaFlow) or 3 5/8" x 9" for the Edelbrock 304s...and they are actually a bit quieter than my open Borla...His stuff is a work of mandrel bent art, but it is a bit pricey. I am also considering the dual cut outs, too...we'll see...Thanks again..

--Alan
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Old Oct 26, 2006 | 05:21 PM
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Originally Posted by hyperzone
BMR makes the upper panhard relocation bar also so that you can fit two bigger pipes over the axle... Could look into just routing to pipes with that out the back. Just a thought...
Yeah , the guy that does the duals can get them (he's a BMR dealer)..We actually are thinking also about going over and out with a 2 on the left type exit...I'm just not sure how good it will look...He has also done duals over both sides of the axle and it looks killer, but he thinks theres more power in going over the one side as its less bends...It was just easier to dump them and be done with it....still in the planning/thinking stages here...Thanks!

--Alan

...its Performance Auto Fabrication and he did a guy's on here not too long ago...A red SS out both sides...
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Old Oct 26, 2006 | 05:42 PM
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Wow... never seen it on both sides of axle... I know of some that have taken it under the axle after they got tired of the X-pipe-axle-dump setup...
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Old Oct 26, 2006 | 08:59 PM
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Originally Posted by hyperzone
BMR makes the upper panhard relocation bar also so that you can fit two bigger pipes over the axle... Could look into just routing to pipes with that out the back. Just a thought...
Yup and it works great, it allows 3 inch pipes to be ran over the axle out the back which is what I had done.
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