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http://www.dieselplace.com/forum/smileys/Hug.gifhttp://www.dieselplace.com/forum/smileys/Big Smile.gifI have been lurking for a few months and just wanted to contribute my conclusions and the outcome of mods made to my 97 chev crewcab 4wd dually. I first puchased the truck in Nov. of 03 with 63000 miles on the clock. I drove straight to my shop and changed all fluids and filters. I use shell rotella oil with 2 quarts Lucas. 6 new tires and an alignment later I was good to go. In the winter with idling and city/ highway mix, I pulled 14 mpg over several tank average. 65 to 70 on highway with no hard takeoffs. All stock with the exception of a K + N air filter. Next I added Autometer boost and pyrometer gauges. When taking off the boost would briefly (3 to 4 secs) spike to 8 psi then fall to 2 to 3 psi. Driving on the highway boost was 0 to 3 psi. Pyro 800 to 900. I hooked my 9000 lb. travel trailer and the truck completely fell down and temp hit 220 to 235. truck wouldn't do over 55 on highway. Everytime I hit a hill the temp would shoot up. I took truck to chevy dealer and told them of no towing power and black smoke. 800. dollars later I had a new gauge cluster and temp sensor. (they said cluster was bad and sending codes for low oil presure to computer which in turn killed my fuel and boost) I hooked to my travel trailer again and the only difference was I was 800. poorer. (man was I pi$$ed) So after doing it chevy's way I decided to try mine. I ordered a new crossover pipe and downtube from Flowmaster. The pair was only 90. delivered to my house. Really nice mandrel bent pipes. The fit was flawless. With the downtube and crossover installed I noticed a slight rumble from under the hood and the underhood temps were noticably dcreased. Next I removed all the old exhaust (including cat) and installed a 3" pipe from the converter flange to a 4" expansion, into 4" pipe, a flow through truck resonater (like on semi's) into a 45, a 90, another 45 and finally into a 5" chrome tailpipe. The sound is not to loud and very deep. I immediatly felt the truck not working so hard to maintain speed or get up to speed. The truck shifted earlier and firmer and boost was spiking 10 psi on take off and I am able to maintain boost by using the pedal. No more fall off on the boost. Upon inspection of the cat, it was 90 % plugged. My under hood temps are greatly reduced even on hot days and the last fuel mpg avg was 16.9 with a heavy foot. Not bad for 4.10 gears. (2100@60) I can hear the turbo whine now and even whistle through the exhaust. I haven't pulled my trailer yet but I did pull a 6600lb bobcat on a 2000lb trailer at 65 with no problems. truck ran about 210 or so with a/c on. Since then I ported to upper intake and removed the "shirt sleeve" from the inner fender to the air box. Next I am planning on putting a cowl induction scoop on my hood and venting each s

I didn't go past the rear axle on mine.
I think you can handle at least 10K ohms fixed resistance on the "B" wire.

Ok great, thats my next mod. The exhaust is really the ticket to begin power upgrades. I'm still working on modifying the hood for cold air intake.

thats not an exhaust thats a stovepipe! nice, now all you gotta do is crank the fuel on that puppy ;) Too many R's to get much better mileage though, mine runs exactly 2000@70MPH.

never thought to go to flowmaster for a downpipe. cant beat that price.

And I found the flowmaster kit # 17220 at summit racing cheaper than at flowmaster. Go figure that out.


Hey Largestar got any that 3 or 4 inch stuff left. Finding it down here might prove next to impossible. You got any pic of your workmanship.


Anyone out there running straight pipe. How that working for You.


Whats the best flowing muffler for these trucksEdited by: bowtie

I wouldn't venture a guess at what's best, but the very first thing I did was to strip the OEM system and go with 4" mandrel bent pipe. Here's the muffler I used:


http://www.magnaflow.com/02product/xl/xlperformance.htm (http://www.magnaflow.com/02product/xl/xlperformance.htm)


I went with the 7" round, part no. 13971. It's a straight thru design. Beautiful sound and boy oh boy, what a difference.

Bowtie, Just go to a large truck dealer or parts store, they can get it. When I get back home I'll take a few pics, I 'm in Winslow Az. right now so give me a week or so. Thanks

Largestar, I was not going to even consider upgrading the downpipe, and never dreamed about the crossover, but now that I've read your post and seen the price! whoa! mine will be here very soon, thanks!

I bet there will be a run on these kits now. My on back order till Aug 23 2004 guess I got in a little too late LOL


Can't wait till it gets here

TDG and Bowtie, I got mine through Summit Racing 1 800 230 3030 (I think) I know Jegs carries them also. I got to run my truck in stages when I did the exhaust. First was the crossover and downtube, then the next day I finished it out. You will notice cooler underhood temps and a slight rumble under the hood after th C/O and D/T. You will also be able to actually hear your turbo whistle. With just the crossover and downtube, no exhaust, you could hear my turbo a block away!!! (it was cool) Truck really zips up to 70 now and doesn't feel like it is straining on highway. All in all I should have done it sooner.

Largestar,
How long did it take you to put the crossover and down tube in? I'm planning on doing it this weekend (got both sitting on the bench in my garage right now). I'm just dreading the thought of trying to loosen rusty exhaust bolts.

Hey LargeStar thanks my are on order (backorder) and i should get them by the end of month.

For the Flowmaster downpipe and crossover kit, try 21st Century Exhaust at 800-276-6399, ask for John. They don't have a web site.

where are they out of? whats their price?

Somewhere in Florida. I did the work last Fall. Sorry, don't remember what I paid but at the time, they beat everyone's price.

I had the straight pipe off the downpipe on my '94 truck recently.
I was amazed at how much motor I could hear.
I've been thinking about doubling the straightpipe and running two 3" from the downpipe back.

I ordered my from summit racing for 90.00 free shipping. Backordered till 23 aug. Checked with jegs they want same price plus shipping and not in stock either


can't wait to get them in

to install the crossover and downpipe only took about 90 minutes, fixing the 3 broken bolts that snapped took 4 hours.http://dieselplace.com/forum/smileys/Cry.gif The fit is excellant so you don't have to tweak anything to get it right. Put a little high temp sealer on the mounting flange of the pipes and torque it down. Oh ya, I found the best way to get on the clamp for the downtube was to remove the air box and go through the top, you might need a buddy to hold it in place while you snug it. Good luck. I'll post some pics of my exhaust in the next week.

Anybody know any reason why the flowmaster kit wouldn't work on my 94 L65? Descriptions says for 95-98


Doug

There's no difference between '94-'99. They all have the 4-bolt flange.


I put a '93 pipe, no flange.


This picture is Canadian Rigger's pipes. The stock '00 downpipe is below, flange still bolted. Aftre market pipe flared at the end for 3 1/2" to 4" collector


http://www.dieselplace.com/forum/uploads/D71_pipes.jpg


Here's what a stock '94 (top) and after market 3" '93 pipe look like.


http://www.dieselplace.com/forum/uploads/F4E_8af_downpipes1.jpg

Where did you find the downpipe on summit? I can't find it in their shop.

Is it worthwhile to replace the crossover pipe, too? It looks like being large enough.

The crossover that comes in the kit is mandrel bent, the stock unit is crimped repeatedly.

Ja, I've seen the crimps, but thought the pipe's still large enough and shouldn't make a noticeable difference?


BTW, I've found on summit:


FLO-17220
Exhaust Kit 95-98 GM Turbo Dsl 3" Down Pipe & 2.5" Crossover Pipe


Price is listed as $104.39. Is that the right kit?

Does summit ship to Germany?

Price went up. The 2.5" crossover is 1/4" bigger. Ask bow how he likes his. He switched the downpipe and crossover then days later switched the rest of the exhaust.

So the kit I've found is the right one?

I've send mail to summit asking for shipping. One can't make the pipes self for that price ...

The problem is that the pipes seem to be rather large. If they were not, I could have them shipped to an address in the US and then have them sent over, as I did with the pump and the gauges. But shipping the pipes could be expensive, don't know ...

lee,


Summit also has 3" -3 1/2" and 4" cat's. Since you can't remove it there.

Ask bow how he likes his. He switched the downpipe and crossover then days later switched the rest of the exhaust.


BOW LIKES HIS

bow: :)

QM,

does it make sense to replace one cat with another? I. e., maybe their cats don't plug the exhaust like the stock ones; if that be, it may be worthwhile.

Anyone tried such a setup?


PS: Seems that the cats they have are for gassers? Aren't Diesel cats different?
Edited by: 0lee

I never tried them but they are billed as performance. the stock unit can be modified/defeated by putting a 3"-4" pipe through it and welding it tight. that way it will look like a cat but run right throught it.

I never tried them but they are billed as performance. the stock unit can be modified/defeated by putting a 3"-4" pipe through it and welding it tight. that way it will look like a cat but run right throught it.


If I had to "keep" a cat this is what I would do. Clean it out and weld a pipe though it. Looks good last long time.

Well, I'm not sure yet what I'll do. The stock muffler should be replaced, too, but I cannot do that legally either. And of course, I won't do anything illegal ...

Well, I'm not sure yet what I'll do. The stock muffler should be replaced, too, but I cannot do that legally either. And of course, I won't do anything illegal ...



Yea Wouldn't want to do anything like that


Edited by: bowtie

I've read enough to get foggy - need BEER! Bottom line, someone, please: when installing Flowmaster crossover and downpipe:


1) what other parts must be ordered? dealer parts?


2) what special care must be taken, what tips can be given, what tools (like blue wrench - some call it cutting torch) need to be used?


3) in a Suburban, with the rest of the system left STOCK, what are the gains? how loud does cabin noise get?


4) does my 98 K2500 actually have a catalytic crapper? if so I will have to fix that as well.


Thanks!

BobT,


I just installed mine this weekend. The only extra parts I needed were 2 doughnut gaskets for the crossover pipe. Don't have the part # in front of me, but they were about $11 apiece at the local stealer. My old ones actually looked ok, and I could have probably reused them. You may need a new gasket for the flange as well.


The only problem I had with my 94 was that the downpipe's flange didn't line up exactly with the cat's flange. Some tweaking on the cat's hanger took care of that.


It was just slightly challenging getting the new downpipe snaked in and lined up, an extra set of hands will really help.


Should be no noise difference.


If your 98 has a cat, you can hollow it out by hammering in a pipe (down the length of the exhaust) many times to break up the honeycomb material, just make sure to get all the chunks out.


Doug