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Real Gains From Exhaust Mods?

M

mha

GUEST
The last time I played with Flowmaster was on a 454. I added K&N first and noticed a slight improvement, not as significant as I'd previously seen on 350 Vortecs. Later I added a Flowmaster and wasn't really impressed. Could be the 454 was already impressive enough and I didn't notice, could be it just didn't really happen. I never figured that one out.

Taking sound totally out of the equation, what measureable performance gains did you see from strictly adding Flowmaster, etc.? I'm mainly interested in how this affected 5.3s but would be curious to hear all thoughts. Thanks.
 
Your looking at about a 5% increase....my advise..throw in some headers along with your muffler to really feel some increase... :B:
 
O.K., now you guys have really got me wondering. You've been great about answering my other stupid questions and there's a million muffler posts on here yet there doesn't seem to be a consensus on this question. I find that interesting. Did you swap for sound or gains? Swapping for sound is cool, just not my deal. If I swap I want gains. How much of a stretch are the gains listed in the ads?
 
I suspect that any real-world gains will be marginal. The truck will FEEL more powerful, because it will SOUND more powerful. Remember, if backpressure is decreased, then low-end torque is decreased with a corresponding increase in top-end power. If you look under the Avalanche you will see that the General has already done a fair job of exhaust installation. Fairly large pipes with smooth bends, a long way from the old days of 1" pipes with 90 degree kinks. There is always room for improvement but I believe the claims you read in the adds are fairly exaggerated. If those kind of gains were available for that little money I believe they would be standard equipment.
 
To realize a real gain from a less restrictive exhaust, the intake side needs to be tweaked as well. That is unless the stock exhaust system is a very poor, very restrictive design. I changed mine with the idea of having a better exhaust note. Any performance or mileage gain will be a bonus. I have a K&N FIPK on order and hope to see and feel a definite performance gain when complete. The next step would involve headers and as mentioned on another thread or two real performance gains should be expected. Also previously stated elsewhere, these types of power modifications tend to move power farther up the rpm band.
 
I've been out of the performance loop for quite some time now. Ever since I put a set of Hooker's on my '67 Nova small block (God, I loved that car!) There seems to be a whole new breed of header manufacturers out there, most of whom I've never heard of. And what with the technological advances in ignition, air flow, engine design, etc. I'm not at all sure what to get in regards to a header system or if it is even worth it.

I've got an Av 1500 Z-71 5.3 with 4.10 gearing. I don't want to decrease what I've got and I know with headers you have to consider things such as tube diameter, length and collector size and length.

Any suggestions on what to get.

Thanks guys.
 
ROPD said:
I've been out of the performance loop for quite some time now. ?Ever since I put a set of Hooker's on my '67 Nova small block (God, I loved that car!) ?There seems to be a whole new breed of header manufacturers out there, most of whom I've never heard of. ?And what with the technological advances in ignition, air flow, engine design, etc. I'm not at all sure what to get in regards to a header system or if it is even worth it.

I've got an Av 1500 Z-71 5.3 with 4.10 gearing. ?I don't want to decrease what I've got and I know with headers you have to consider things such as tube diameter, length and collector size and length.

Any suggestions on what to get.

Thanks guys. ?
Click to expand...

Three easy answers: TOG, JBA and ASM

Checkout Tbyrne - exhaust section - good starting point.

I have TOG's, very nice, would have liked coated.
>:D
 
gandolphxx said:
Three easy answers: TOG, JBA and ASM

Checkout Tbyrne - exhaust section - good starting point.

I have TOG's, very nice, would have liked coated.
>:D
Click to expand...

Gandolph, are any/all of these headers of the tri-y design?
 
Steelheadchaser said:
Gandolph, are any/all of these headers of the tri-y design?
Click to expand...

First an education Thorley Tech basics - a fair document on the concept.

It takes energy to push disorganized exhaust gases out through a vehicle?s stock manifolds. Headers don?t ?make? horsepower ? they simply relieve the engine from the task of shoving exhaust out through stock manifolds. Installing properly designed headers frees up the energy previously wasted pushing out exhaust, and allows it to be used in propelling the vehicle. This increase in efficiency brought on by the installation of headers can be thought of as ?free horsepower.?
Click to expand...

I believe that the ASM's and the TOG's would fit in this category, I am not familiar enough with the JBA's to comment [paging Butch] ;D
 
I have the JBA ceramic coated hearders on mine.., they use what they call a Fire Tube Collector design.., its a way of making the Header perform like a Long Tube Design... Im very happy with them, and did not lose any Bottom End Power..., noticeable improvement from 2500 on Up..., but dont expect Miracles with just adding Headers alone......
 
Butch,

I was wondering what, if any, gas mileage gains you got with the addition of the headers and Borla exhaust. I've kept track of my MPG since the truck was new via a computer program. So far, over 9,000+ miles, I've gotten 14.24 MPG. On the road I'm getting anywhere from 15 to 16. Around town is what kills me. I blame it on the 4.10 gears but I've gotten used to it and love the truck. Also, in regards to the Borla system. How is the sound and do you get any resonance in the cab?

Thanks.
 
I haven't really kept any good records on the mileage changes..., but did seem to notice an increase if I dont step into it with the Headers, and Exhuast., the tone on the Borla is really nice, and mellow at idle, and cruising..., fairly load when You step into it..., no resonance in the cab at all........
 
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