will dual exhaust benifit my 3.4 l engine or should i just go with single.

 

Without anybody having dyno results, I'll say stay with single.

 

Single can be made to perform just as well as dual and in some cases better. It all depends on the operating characteristics of the motor and how well you can make the exhaust scavenge.

 

A 60 degree v6 (2.8, 3.1, and the 3.4) in a truck doesn't wind enough RPMs to benefit from duals. You will be much happier with a single 2 1/2 inch exhaust system.

Truth of the matter most vee designed engines in street driven trucks never see the RPMs that the full benefit of duals even makes sense compared to keeping the torque higher in the lower RPMs like a properly sized single exhaust does.

 

Gotta agree with these guys. I do not see how these trucks could benefit from having true dual exhaust, unless serious engine modifications have been performed- porting heads & intake manifold, cam, detailed tuning. Stick with a 2 1/2 single in system. If you want the look of duals, get a single in/dual out muffler and see if a shop can fab something up. Looks like the gas tank would possibly be in the way though.

EDIT- If you have a 3.4l V6 and not a 4.3l (I'm playing Devil's advocate that it might be a typo since I don't recall the 3.4 going into Blazers, but never know if a swap has been done), then I can assure you from the dyno numbers F-body V6 guys have done- duals on those engines actually do not gain as much HP as a single system does due to a drop in back pressure (could be remembering wrong about the back pressure, been a few years). Again, the way to get around that slight loss is custom tuning which is going to cost.

 

(playing devil's advocate)
Hes got a 2.8 (said in other posts) and the 3.4 is a common direct swap for it. The factory system on a 2.8 truck is either 2 or 2 1/4 I can't really remember its been so long since I've had a stock one. The 2 1/2 is an upgrade but since the displacement is so low (even on a 4.3) it doesn't have any gains to go any bigger than 2 1/2.

I also highly suggest against ever running a "true dual" on anything as some type of balance pipe (x or H) helps the engine.

The back pressure thing is a sore subject and everybody has an opinion on the subject. From personal experience I've found the 2 1/2 inch single exhaust keeps the power in a more useable RPM range for most any street driven truck. Now if you want to try to be driving around like a ricer bumping a rev limiter all the time sure duals are the way to go.

 

I know the stock piping on my cousin's 2.8 Camaro was 2 1/4, so I guess it'd be the same on an S-series truck. The general rule I was taught on upgrading exhaust pipe diameter was to not go more than 1/2 inch bigger than stock, and often times 1/4 inch upgrade will be a better bottom end gain.

Sorry, I kinda fuddled by saying "true dual". I'm still used to f-body talk and when someone talks about going to "dual" exhaust, 9/10 times they mean a single in/dual out muffler to have the dual look. On those forums we had to ask if thats what they meant or if they wanted real duals. Just been kinda automatic in my thought process on duals over the years to include an H-pipe or X-pipe in my thought when saying "true duals". Its a habbit I need to break haha.

 

so just a single exhaust with 2.5 inch pipe

 

i may also go with the dual look with resonator tips instead of mufflers

 

i can get 2.5 inch stainless steel pipe at work that should work right?

( the pipe will be free leftovers )