Well, tommorow "blue beast" is going in for a new exhaust system, turbo-to-tailpipe. I have a few questions here about this. Is it best to have the old cat removed completely (this is a 1995)? If it is, is the truck going to be constantly smoking or doing something goofy without the cat? I assume there's no electronic sensors or components in the cat. I just want to go to the shop here in town with some background knowledge. The price seems not to bad ($480.00 installed--canadian). They custom, mandrel bend their own systems and use a flow-through Magnaflow muffler. I am planning on a 3 inch throughout. Should i go for 3.5" after the downpipe or will 3"do it? Lastly is the AF box. In the 95' there is the plastic snorkel in the fender i am assuming. A few people suggest getting rid of it and hollowing out the port into the filter box. Was that snorkel not designed for something, or did GM realize it was useless and got rid of it in the 1996+ models? I don't want the filter completely covered in crap because of modification to the stock design. Is it safe to monkey with that? Any suggestions would be appreciated. Thanks. P.S. she 0-60's in 13.5 sec. i'd like to work on that a bit.

It cost me 130.00 plus 100.00 for the downpipe kit for my 95 GMC. I have no muffler or CAT and I love it. Oh course you can always go back and have a muffler installed and spend the money then but after you by it and then decide you would like to have it removed you lost that money. Anyway thought I'd throw that out for you to ponder

Your 95 is definitely completely emissions stupid, upgrading the exhaust and removing the cat is THE best place to start upgrading any diesels performance. Smoke will be reduced from better engine breatheability, no trouble light for sure. I paid $300 for my exhaust, also CDN dollars, in 3" aluminized and I have no complaints. A hi-flow magnaflow muffler will be quite loud, so be ready. I also removed the snorkel from my fenderwell, and whatever GMs intentions were, well they weren't for performance and I have noticed no change in filter 'dirtyness' between normal cleanings.

I would open it up intake and exhaust. more flow is more go.

The snorkel was there to pass cool frontal air to the intake, bypassing engine bay heat thru the fender.

Woulda\coulda\shoulda worked, but the down-low inlet would pack-up with snow during the winter, leaves and junk during else.

TSB said s-can it.

Would help to get that cool air back there, some other way, tho......

Silvy, I see on your sig you list your truck as an L56, with EGR right? I mentioned before that these trucks are emissions stupid, disabling that bad boy and removing the extra casting in the intake will help you out as well.

That's funny. The guy I talked to said that the magnaflow muffler is installed to get rid of the in-cab "drone". TDG, your telling me that that things going to make a whole pile of racket? Am i better off to have it straight-piped like bowtie has suggested. I just want a nice deep growl with some turbo sing. I don't want to be completely obnoxious with it. Thanks for the advice!

Actually, a 6.5 sounds sweet straight piped...I'd try that first.....it's easy to put a muffler in later if you need to.....

The snorkel was there to pass cool frontal air to the intake, bypassing engine bay heat thru the fender.

Woulda\coulda\shoulda worked, but the down-low inlet would pack-up with snow during the winter, leaves and junk during else.

TSB said s-can it.

Would help to get that cool air back there, some other way, tho......
Can you give me more info on "canning" it whats involved in removing it and what else needs to be done at that time

Here Bowtie:

http://www.kennedydiesel.com/

Check out their tech tips section for the 6.5. They have some pics there you can follow.
I'll go for the straight pipe and see how it sounds. I like the idea of being able to put in a muffler later, if neccessary

I think that's been posted before, bowtie - QM, or over on Kennedy Diesel site.

At any rate, my truck is pre-88 style, and I don't remember all I had to do when I was stripping my donor - maybe someone with '88-up can give you the particulars - besides 'remove the battery and yank hard' ;)

I have to admit, I don't have a GREAT deal of experience with Magnaflow mufflers, I did however have one put on my old diesel rabbit, and it was EXTREMELY loud, roared and crackled at high RPMs. Here's what I have now, and I highly reccommend them for anyone else....

www.goravin.com

When I picked up the truck with the new exhaust and hiflow muffler, I was expecting something like the old rabbit, and I was shocked, it was quieter than it had ever been, muffled out all the harsh exhaust sound and what remained was deep tone and turbo whine, better than I could have asked for.

After the 3" downpipe i went 4" all the way to the back with no muffler or soot trap on my 00 truck, we had the muffler shipped with the exhaust to the shop in case i decided to install it later because it might be to loud.... the muffler never got installed.... the sound is sweet, only raps when your foot is in it and my foot is in it alot, cruising down the hiway is a little louder but thats what the volume button on the radio is for...

Remove the 1/4" nut behind the battery on the firewall. Then grab that plastic snorkel and pull it ot of the fenderwell. Easy as that.

Well, she's all done. 3" downpipe, 3" for the rest of it too, magnaflow straight through muffler, chrome tip. The system looks pretty nice. Much deeper idle tone, sounds good. What surprised me is that it is not really any louder while driving than with the stock system. You can however lightly hear the deeper tone. The turbo reponds faster now but the only disappointment I guess is there was very little increase in turbo whine. I will work on the air box a little to see if I can get more wind input. I take it there is no need to replace the snorkel with anything, just simply take it out. Thanks for all the tips guys, it was a big help:D