exhaust opinions?

[DaveNY]

Considering next mod on truck and have decided to uncork the exhaust. Ive got a pretty good guy with a shop close by and figure his 3-3.5 in. is as good as any kit,would like a little input from the forum. Will probably end up with ECM from Bill Heath in the future.
Thanks Dave

[ogrice]

Do it.
I have a BD kit on my rig. You will feel the difference from stock hands down.
I don't know how far you are gonna with the 6.5 as far as mods go. I have the only 6.5 in my area and a lot of Ford and Dodge guys look at me funny when I stop to put diesel in my truck.

Must be because mine is paid for.

[DA BIG ONE]

Consider, porting exhaust port of turbine housing backpressure is the biggest issue w/GM-8 turbo at boost. Too little boost + more fuel high egt's, higher boost w/more fuel lower egt's, but IAT climbs because of backpressure.

3" is small and so far the only option for our down pipes because of space constraints, this is a limiting factor after turbine backpressure.
See: http://www.usgear.com/alert.htm However, some tinkering w/downpipe, maybe even splicing another section of pipe to it and all meeting at say a 4"+ exhaust from there would be the best option, I'm considering this option.

[DaveNY]

One more payment mine was used. I will probably stop at the heath ecm. although an old hotrodder from the 60's. I wont rule out getting carried away. my main concern is if a 3" less the cat will give me significant improvement prior to and after the ECM upgrade.

[Ezzie]

I had the turbo in my '95 off last night and got looking at the downpipe between the turbo extension and the rectangular flange under the cab. Is that pipe supposed to have a bunch of flat spots in it where it passes through close to the frame? The one on mine looks sooooo... restrictive, its simply got to produce too much backpressure. Are they all this way or is mine a frankenstein?? What are the aftermarket kits like? Do they replace the OEM downpipe as well?

[DA BIG ONE]

Originally posted by Ezzie:
I had the turbo in my '95 off last night and got looking at the downpipe between the turbo extension and the rectangular flange under the cab. Is that pipe supposed to have a bunch of flat spots in it where it passes through close to the frame? The one on mine looks sooooo... restrictive, its simply got to produce too much backpressure. Are they all this way or is mine a frankenstein?? What are the aftermarket kits like? Do they replace the OEM downpipe as well? Don't even consider the system if downpipe is not included.

[Dvldog8793]

Howdy
Short of the cat and MAYBE the muff, the factory downpipe is probably the most restrictive part of the factory system.
IMHO- 3.5 is a MINIMUM size and get rid of ALL other components. If you use 3inch pipe then having a MANDREL bender is a must. Make it as straight as possible. The bigger "un-squashed" downpipe is a major factor. Be carefull removing/installing the downpipe clamp, it is stainless steel and will strip/gall easy.
The Exhaust and air intake were the 2 biggest seat-of-the-pants mods that I did.
Hope this helps...
L8r
Conley

[Kennedy]

I have dyno proven the benefits of a good exhaust system. Make sure it is mandrel bent pipe like the KD system. Lots of happy KD exhaust owners on this site.

[Cowracer]

I'm one!

Tim

[woody]

Gents,

Recently installed KD's 3 1/2 system on my '93 K2500. Took a little manipulation to get the non-dented DP to clear firewall area, etc, so there was no body/framerail contact anywhere when truck was lowered after installation. But, measured almost a 2mpg improvement in economy... after I settled down and kept my foot out of it. The original DP had considerable denting for clearance, but a knowledgeable engineer told me GM considered this in the design, and at stock power levels shud not be an issue. All I can say is that the new KD system does offer measurable improvements to my otherwise stock truck.

The new "throaty" sound is sooo sweet, you want to get on it more. There is a definite seat-of-the-pants performance improvement. It is louder, and things rattle more than stock until you find all the loose things that probably needed attention anyway. Took a while for the novelty to wear off and mpg comparisons could be realistically performed.

Would I do it again? You bet, the KD system definitely works. Just took 13 years for the original system to wear out and justify replacement with something better.

All best -Woody-

[DaveNY]

Thanks All, Got Info that I wanted. Really appreciate this site,sure saves alot of trial and error.
Dave

[sturgeon-phish]

I went with Kennedy's. A little more money BUT WORTH EVERY PENNY. MPG improved, acceleration temps, all pluses no negatives. Huge difference towing. And it's not that much louder than my stock with the cat gutted.
Jim