Exhaust Question

[maverick2]

I recently picked up a '94 2-dr Tahoe with the 6.5 Turbo Diesel. Rig has 90k original miles, is in mint condition, and is 100% stock (right down to the !@#$% catalytic converter). It's got 3.73 gearing and averages 17-18 mpg. I use it mainly for work, running up and down state highways (Idaho) getting to and from abandoned mine sites. I tow very little with it (we have a Duramax for the heavy stuff). My first mod is going to be to ditch the catalytic converter, so thought I'd upgrade the exhaust system at that time. Knowing I tow very little and am hoping to make gains in fuel economy and and engine durability/longevity, I'd like to know the general concensus on upgrading to a 3" cat-back system w/ high flow muffler (assume the cat gets lost in the process) vs a 4" turbo back system. (Cost for the 3" system is $200, and cost for the 4" is $500.) Thoughts and recommendations (again, keeping in mind the primary goal is economy, and the secondary goal is performance)???

Thanks in advance.

[DmaxMaverick]

If you aren't towing heavy, often, 4" isn't necessary (no EGT problem), and any other gain will be negligible. Save the $300 for a good chip and injectors (KD (http://www.kennedydiesel.com), my suggestion). A timing set should follow shortly. Your gearing is good for all-purpose, DD and towing. I suggest focusing on economy from there, and some performance will naturally follow. Also, a mandrel bent downpipe would be a very nice compliment to your new plumbing.

[JohnC]

Don't get your hopes up too high...

Unless the converter is plugged, I'd be surprised if the mileage will go up even 1 mpg. Performance on the other hand, can be improved. Most likely the Tahoe is an "S" engine with EGR. If you can get "F" programming and ditch the EGR manifold (or at least block it off) things will improve considerably.

[motown]

you might want to talk to your local muffler shop or do it yourself i went to a place that sells heavyduty truck parts and bought some 5in pipe 120 bucks 45 30 bucks hanger 15 bucks 165$ for 5 inch exhaust isn't bad

[6.5 Detroit Diesel]

X2 on what DMax said. If you aren't doing heavy with it, save the money for something else. And do the downpipe for sure. That and open up your intake system. ;)

[Artworks]

I installed Kennedy's system. Decent $ and service. Fairly easy, half day with minimum of hand tools ( 18V dewalt rec. saw helps) Real nice sound, good 'fit'. Everything still tight after 2 years.

[maverick2]

Thanks for the feedback. Based on how I use this rig, I was skeptical that an oversize exhaust would do much for me, and the general consensus seems to agree. Any suggestions on where I can pick up a new mandrel bent downpipe? I'm not seeing much available there, unless it's part of an entire kit...

Follow-on question is whose/which chip would you recommend for my application.