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Does mufflers really hold back hp?

6K views 28 replies 14 participants last post by  JAYDBPR 
#1 ·
Being that i need 40 comments...i figured i wont search for things i want to ask about! Anyways....

On pervious cars and trucks i have owned...there has been zero difference on hp with or without a muffler....

Curious if theres any truth to it...or just butt dyno results..

And if it does...which mufflers help the most? Also....does it just help peak hp numbers or across the board
 
#5 ·
There was a 14 RWHP difference at the 500 RWHP level with no mufflers vs GT mufflers. Dyno chart on other board. Search "Stock G8 GT mufflers cost 14rwhp at 500rwhp level" on there if you want.
 
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#15 ·
June 5th I will find out. I am testing the rod mod intake back to back. I will also pop off the mufflers really fast and test with them off. Will post up once done.



In an N/A setup, 14 rwhp is a lot. Ported heads give 15-20 rwhp and costs $1k-1500, to put it in perspective.

Mid muffler + dynomax muffs were pretty quiet, but still too loud for baby hauler. I'll probably switch to that setup once he's a little older (if I still have car).

All of this power is through the curve too, so that's easily 1-2 MPH in the 1/4. Pretty big difference.

 
#6 ·
I don't know about HP but they certainly are no fun XD // I've got the stock mufflers on my GT (infact it's all stock) and I cannot wait to get some flowmaster 40s on it. I had the flowmaster 40s on my 96 Z28 and on my 78 Firebird Formula (had a 400cu in it with no CATS OBV and tru dual chopped b4 the rear axle LOL... safe?). They sound amazing! I would love to hear the way some 40s sound with this 6.0. I'm just trying to decide if I want to give up the quiet ride that is so peaceful sometimes. Car is so quiet inside I hate to do it... but having a 6.0 and not being able to hear her pur is pretty painful, hehe.

:burnout:
 
#7 ·
I highly highly highlyyyyyy doubt 14 rwhp off taking them off......if not everyone would have them cut off....

But i have arh headers and catless exhaust sitting at the house waiting for me to put on...I'll see if its still to quiet after that...
 
#8 ·
When your headers and catback are installed, you remove 3 of the five mufflers on the car. It will sound better, just maybe not the volume you want of are willing to accept. If you do opt for louder mufflers, keep the originals, just in case you have a wedding or funeral to go to.
 
#18 ·
I had cutouts installed and had an x-pipe installed in place of the center muffler. here is my dyno sheet that shows a 10 whp difference with them open compared to when they are closed. there is a slight bump in bottom end torque with them closed and going out the stock gt mufflers, so there is some added back pressure. The blue line is with the cutouts open and being dumped before the last turn in the exhaust, the red line is with the cutouts closed flowing through the stock gt mufflers.
 

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#29 ·
They sound pretty good. Similar to Borla, of which I also had. Just blows that they are aluminized steel. I had them installed on my car before the SS mufflers. Ran them for a summer, cost me $50 for the pair brand new on Ebay.
 
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