WVman

iTrader: (3)

I'm thinking about just swapping out the stock muffler for a free flowing muffler. I'm just not sure if it will lose some *** on the bottom end with a straight through 3.5" all the way out. I read on here somewhere one of you guys with the 6.2 lost 3 tenths in the 1/4 by adding a straight through 3.5" muffler. So after reading that I'm wondering if I should do a custom 3" catback. I know with the 3" it will keep the low end and may even pick a little more up down there. I tow a lot so I don't want to lose ANY lowend.

This is the 3.5" muffler I would swap for the stock one. Jegs has it for $75
http://www.pysales.com/iw_products.m...46?company=ppe IMO Pypes has one of the best sounding mufflers. I was a Magnaflow guy until I heard a Pypes system but to each there own on the sound you like.

This is the 3" muffler I would use if I do a catback. http://www.pysales.com/iw_products.m...36?company=ppe This one is $65 at Jegs. They have a 14" also.

Here is all their mufflers.
http://www.pypesexhaust.com/mufflers.html

So what are most of you 6.2 guys running 3" or 3.5"? Sorry for the long post and thanks for any help.
Mike

supercharged680

iTrader: (1)

3.5"..

WVman

iTrader: (3)

What catback do you run on your ride?

markislive78

Many of the aftermarket exhaust companies are downsizing to single 3'' on the 6.2's, Borla even uses a 2.75'' head pipe on their Sierra Denali kit. You would have to think they are testing various sizes before putting a kit into production...

Daryn

iTrader: (19)

throw a electric cutout on it

09sierra6.2

and everyone i talk to says BACKPRESSURE doesnt give you HP??? hum then why on earth would big name companies make smaller size exhaust to bolt up? i run the big body magnaflow in place of my stock muffler all 3.5" and had it ran out the back just like factory except took out the resonator.. sounds good not loud at all but havnt got my lt's yet either so it will get better! imo you dont need to much of a free flowing (by free flowing i mean no mufflers) exhaust unless you have a built motor then i could see where you would need it and with a mostly stock truck and just bolt ons especially dont see a straight exhaust doin anything but makn noise!

GMCtrk

iTrader: (27)

The answer is increased exhaust velocity, not increased backpressure. Increased exhaust velocity aids in more efficiently evacuating the cylinders of exhaust. On the other hand, an increase in resistance to flow increases the amount of energy needed to get the exhaust out. End result, less power to the ground.

WVman

iTrader: (3)

I have noticed that also markislive78. Thanks!

Here's some info I found on my search for an exhaust.

A 2.75” (stock) single system is good for a 310hp engine with zero loss…
A 3” Single system is good for a 370hp engine with zero loss…
A 3.5” Single system is good for a 503hp engine with zero loss…
A 4” Single system is good for a 657hp engine with zero loss…
A 2.25” dual system is good for a 457hp engine with zero loss…
A 2.5” dual system is good for a 513hp engine with zero loss…
A 3” dual system is good for a 812hp engine with zero loss…

These numbers are assuming that everything else is set up perfectly. The muffler must flow as much as the open pipe to get zero loss at the listed hp levels. Using a muffler with a larger inlet/outlet diameter than your exhaust pipe is a great way to get more out of a smaller diameter system since the muffler flow will be able to match the straight pipe flow.

I'm leaning towards a 3" catback with the 3.5" muffler I have listed. I guess I could just do the 3.5" muffler first and see how it works out. I don't want it too loud after I do my headers, my little man likes to watch his DVDs when he is in the truck.

WVman

iTrader: (3)

I'm asking here, but from my experience a smaller pipe will give you more low end and take some from the top if it's too small. A bigger pipe will lose a little on the low end but gain on top. It happened when I added a 3" catback to my 91 Chevy with a TB and 350. It lost all kinds of low end with the 3" on it. Thanks for the help guys!

WVman

iTrader: (3)

Your set up sounds like what I was going to do at first. Did you lose any low end with the way you did your exhaust?