Hi, Own 93 6.5 2500 truck & 5th wheel Weight 17500, 4or 5% grade 25 to 35 mph. Have read just about all post. Wondering would cutting crossover pipe and going out with another exhaust help? or would it be better to go to a 3 - 4 inch down pipe? how about as I have read use a 3in downpipe and cutting the muffler out and useing a straight pipe. Would any of the above really help? Love the truck empty almost cannot be beat from standstill up to 60. Not bad. Thanks.

flowmaster has a downpipe and crossover kit that you can get from summitracing.com. that should be your first upgrade along with removing the cat and muffler and going 4inch all the way back. next step should be some gauges. read the faq's at top to learn more.

I don't think you want to cut the cross-over. Won't you lose a lot of exhaust volume needed to spin the turbo?

Are you talking about the size of the down pipe or the whole exhaust? The downpipe and crossover from Flowmaster can't be beat for price, and are much better than the stock pieces. Cheapest place I've seen them on is http://www.performancepeddler.com/detail.asp?PRODUCT_ID=FLO17220 for $100!

I'm very pleased with my 3" exhaust, but there are several on this site that have bigger than that, the bigger the better when it comes do exhaust, but 4"+ is overkill on a 6.5 IMHO. Have you ever replaced your timing chain? Since your truck is now 12 years old, it would be worth considering, new chain set will restore your cam timing and let the engine breathe a little easier. Your mechanical pump and wastegate on your turbo are easy to tweak for more power too. Exhaust upgrade should be first, and I would replace the timing set next, then boost/EGT gauges if you plan to do anything with the pump/turbo.

let it breathe. suck and blow. thats all there is to know. 4" will work much better. especially with the bends in the pipe that restrict airflow. god i wish i could put a 4" downpipe on this thing.

I have a 3.5" exhaust for my 95 Burb from JK. I have a friend who has a 97 who put in a 4" exhaust with little or no performance gain over mine. His 4" looks good and sounds terrible (too loud) but, IMHO go with the max performance of the 6.5 capabilty and not the over kill. Why walk around with an oxygen bottle to breathe better when normal air works just fine (except in the inner large cities).

G turbo,
welcome to the site, take a minute to go to users CP and update your sig, and spend some time in the FAQs & welcome note at top of this forum, I added some tips with max bolt on stuff for more power, I manage to short haul 200 mile pull with CGVW up to 24K couple of times a year 70mph flat to 50mph on grade. Will eventually go into the engine for a little more grunt/longevity.

gturbo65c

I think you are going to look at more than just the exhaust to get what you are looking for. But before you do anything get an exhaust temperature guage before you do real damage from high exhaust temperatures pulling under those coditions.

Once you open up the exhaust and remove the snokle from the right side front fender so the thing can breath I would consider an intercooler first, a Heath Turbo Master, and a reprogramed PCM. These are the principal modes to my truck and I pull 5% grades at 55 mph totaling 16.540 lbs.

Good Luck

Are you sure that the 4" downpipe you saw was not for a Dmax? I have never heard of a downpipe that big for the 6.5, not to mention you'd have a hell of a time getting it in there. I have heard of a couple 3.5" units, but most common is the 3" and I can say yes the 3" does make a huge difference. after that, you can hook up whatever size exhaust you want, however be sure to check clearance between crossmembers and the cab floor before you go out and get a 4" or more. On my crew cab, I only barely had room for a 3.5" pipe between the cab and crossmember without ovaling the pipe. As far as downpipes go, unless you are going to push the mods to the extreme a 3" is plenty IMHO, plus you just can't beat the price of the Flowmaster crossover/downpipe combo.

The difference is in '94 they started using a 4-bolt flange at the end of the downpipe before the soot trap. I don't see why the 4" for '94-'00 wouldn't work but it might have that 4-bolt flange.

Double check that 4" down pipe size AFIK no such animal that will work on a 6.5 of any year; 3" yes, 3.5" maybe with come creative finessing, but a 4 " don't see it happening myself unless you sqrunch it up like a GM one you are ripping out.

Ok now that its a 3in pipe, I can make sure thats what is offered for the 93. Now rip out the old snorkel any suggestions on a new air filter and what size? Thanks again. gturbo.

K&N, AFE, Amsoil, and Kennedy all offer the flat rectangular re-useable filter elements for '92-'96. I paid like $80 for the k&n 6 years ago before I knew there were other options, heck there may not have been any other options back then.

I think this may be my last question, all my other questions were answered. When everyone was talking 3in or 4in are we referring to ID or OD size? Thanks.

mine is 4" id. i have never heard of a 4" downer. it would have to be beat up to get it in. even if you got it in how would you fit it up to the turbo? that has to be for a d-max. even so dont think you could retrofit it. if anyone does i want to know how. would love to have a 4"down pipe.

grape fit a 4" but I think he cut a notch into his frame to fit it.

qm, how did grape fit it to the turbo?

Hey Guys I think I might have screwed up the 3in or 4in I was referring to was the exhaust pipe from the downpipe back. Sorry for the misstake. Gordon.

Here's an update of the exhaust system. I have installed the 3 x 3.5in downpipe and from the 3.5in it goes past the tranny and then goes to 4in the rest of the way. At last I know that the turbo works, I can hear it. Will say you know that the 4in straight thru muffler is there. Thanks for all the help. Gordon.

I have a 93 2500 ext cab LB, 6.5, 4.10 gear, 3in downpipe to 4in, K&N filter, 70000miles

Hey Gordon thats a low miles truck. What part of the world are you from? I know what TDG said ......but with such low miles I would not mess with timing chain and gears unless you do the cooling upgrade, when you change the water pump your 80% to changing the timing set. Does your truck over heat when you tow?

qm, how did grape fit it to the turbo?He put on an aftermarket turbo.

Thanks, the only miles this truck gets is in the summer, no winter driving. Bought the truck 6 years ago with 28000. Probably the hottest it gets is about just a little above the halfway mark. That was last year. However just put a new radiator on 2 months ago. Had to replace the clutch on the fan also, that made a big difference when it shuts off the temp will be at the first mark. I know I got to put a better gauge than the factory one. Gordon.

grape fit a 4" but I think he cut a notch into his frame to fit it.qm, i dont know about you but i dont think i would want to hack up my frame in order to get a 4" down pipe in. even if you changed the turbo and put a 4" downer in, there would still have to be a better way to run it instead of sacrificing the integrity of your frame. somebody on this site has to be able to come up with a better solution. dont you think?:think: :weld: