GMT 900 Trucks General Discussion 2007 - 2013 Trucks | General Discussion

Exhaust cut-out.

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Old Sep 28, 2010 | 01:57 PM
  #21  
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Originally Posted by blackjack325
yeah, i know about the "baffles" on the vettes... but thats a 6.2L SC engine.

edit: and i tried to duplicate the same way that the ZR1 opens up its exhaust (Z06 too) and track times were the same.
What exhaust do you have, it might be a pretty free flowing exhaust.
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Old Sep 28, 2010 | 05:03 PM
  #22  
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Originally Posted by blackjack325
thats crazy .20!!

i have longtubes, ORY, to a 3" inlet 2x2.5" outlet borla... have seen no drop in times by just opening my Cut out
Yeah it is crazy, especially when you figure that with my truck with the cutouts open, it felt much slower. And well it was down low, I can't remember what I lost on the 60' times. It must have really helped out on top though. Prior to my runs with the open cutouts I would have sworn I lost power and 2/10's or more in the 1/4.
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Old Sep 28, 2010 | 07:09 PM
  #23  
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Originally Posted by fredkj3
it all depends on how restrictive your muffler is. I have personally ran it open vs closed thru a flowmaster and picked up two tenths with it open. id be willing to bet it helps this guy out at least a tenth.
Flow master was your problem lol
Originally Posted by outlawz2004
you dont need backpressure, you need velocity.
Can you define velocity for me then? lol
Originally Posted by fredkj3
for the people who still have stock exhaust system it may not make a big difference because your still going thru your restrictive manifolds and cat converters... but people with headers and ory the muffler is the most restrictive thing so it would make more of a diff to them

I have picked up .2 before playing with it... I had headers and high flow cat. on a a V6 firebird.

don't laugh I was 17... ha best time was a 15.3 haha
Newer truck have good flowing cats. The manifolds are probably what sucks


We will see soon I guess. My best time is 15.2 with a magnaflow I've done nothing different to the truck other than the cutout. Not saying its going ot do a difference but we will see.
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Old Sep 28, 2010 | 10:27 PM
  #24  
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i should put a cut out on the stock 6.2L and see what happens... i know it would make a difference with the stock muffler...
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Old Sep 28, 2010 | 10:42 PM
  #25  
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After my build we put on the same exhaust I had on the truck previously and it made 28hp and 34#lbs less than open headers. True dual 3" XR-1's, off-road x-pipe with cutouts is is the works.
With a minor bolt-on motor (muffler, CAI) you won't see a difference.
Add 42ci, 11.5:1,cam, heads, and they are definately worth it.
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Old Sep 29, 2010 | 06:30 AM
  #26  
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Yeah, best time for me has been 14.95 before the torque converter and pulley. On the street, my buddy and I were using the Edge tuner "drag strip" and times were consistent with the time I ran @ the track.
I was trying the closed exhaust, then opened on the top end and vise verse. It felt like it had less "go" on the bottom with the exhaust open but i just didnt see it transfer to the 1/4 times.
After the 3000 stall and pulley, have seen times on the Edge "drag strip" drop to 14.6X (traction not all there) on the 22's.
Dying to take it to the track

Got the DOD delete kit and 4.10's on stand by, waiting to buy my cam, rods, springs.... wonder what that'll do to my 1/4mi times?
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Old Sep 29, 2010 | 06:53 AM
  #27  
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I will be going to the track soon! I don't have cutouts, but I do have exhaust that's easy to unbolt. I'm running a flowmaster dual in & out, and hoping for a big change in et's!
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Old Sep 29, 2010 | 07:46 AM
  #28  
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get rid of that flowmaster bro....

borla or magnaflow for our trucks
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Old Sep 29, 2010 | 07:56 AM
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Originally Posted by blackjack325
get rid of that flowmaster bro....

borla or magnaflow for our trucks
If this is to me.. I love the sound of flowmaster & always have. If theirs a big differents I'll buy cutouts!
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Old Sep 29, 2010 | 08:27 AM
  #30  
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Originally Posted by fredkj3
i should put a cut out on the stock 6.2L and see what happens... i know it would make a difference with the stock muffler...
Different motor. I have a 5.3. if you don't see a difference with a 6.2 with or without stock muffler and open cutout there is something wrong. Bigger motor requires more air flow.
Originally Posted by mhotrodscooter
If this is to me.. I love the sound of flowmaster & always have. If theirs a big differents I'll buy cutouts!
cutouts is not a brand. And flow master resticts air flow not allowing as much flow in the exhaust which doesn't produce as much HP.
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