simple exhuast idea

speedshifter · April 8, 2004

hey guys, '97 yukon...

k, magnaflow stainless cats are going on soon. my ghetto mufflershop dual cat backs have to go. so im thinking cheap, simple, and good performance. What do you think of a dual in/dual out 2.5" stainless flowmaster muffler after the cat flange (basically same location as my current muffler, see my website) and then a few inches after the muffler (6-8") have dual turndowns. Its cheap, simple, and eliminates the need to go over the axle and out the back which reduces restriction.

I was thinking like the 50 series suv muffler (the 30% larger one), something that flows well, and sounds good w/o being obnoxious.

What do you think? Any flaws in the plan I have not seen?

Thanks.

elboberino · April 8, 2004

That's pretty much the setup I got going with my muffler. I have the Flowmaster 40 Series Original coming off a Gibson headpipe that i had from the crappy gibson setup I used to have. Its single in 3" and dual out 2.25 or 2.5, i can't remember which. Then about 3-4 inches after the muffler is the turndowns. I like it because it looks clean and mine really sounds nice, but I like the loudness I get from the 40 series. The only problem I think I might encounter within the next few months is getting the emissions checked. Those litlle punks down at that place will not like having to figure out a way to get their equipment in there.

I also like the setup because it is not something that everyone else has. Its not two big pipes sticking out the back and there is not big chrome pipe sticking out. They just get ruined anyways.

Good luck with whatever you do.

speedshifter · April 8, 2004

I know what you mean, I got chromes coming out each side behind the wheels w/o mud flaps and those things always get dirty.

As far as emissions, I have a '97 truck which is OBDII, so they do the IM240 test here. Basically after I get my new cam and stop throwing codes, then can just plug into the ecm and see that there is no codes and I'm good to go.

If they do want to throw in on the rollers and stuff the sniffer up there, I'm just gonna bring along one of those rubber ehxaust hose exstensions from work and throw it on there for them so they dont have to climb under there.

I also gotta finda a dual in/dual out 2.5" muffler. THe flowmaster SUV 50 series only comes in 2.25" dual in/dual out.

Later

elboberino · April 8, 2004

I am curious about the tubing you are talking about for emissions. That sounds like a good idea and might save the guys down there a lot of time and anger towards me.

speedshifter · April 9, 2004

Its standard rubber hose that any shop will use to run a car indoors and route the exhuast outside.

I just realized that I cant get away with turndowns because I have an SUV and the fumes will come up from underneath the truck and work their way into the vehicle somehow. I don't know about u, but I don't like breathing CO.

Sounds like that simple exhuast idea will only work in a pickup truck application.

I still gotta think of a way to keep my exhuast from going over the axle. I like the idea of less piping=more performance and its cheaper. I also gotta watch out cuz I have smittybilt nerf bars and i don't want the exhaust hittin them either.

I guess its back to the drawing board on this one.

elboberino · April 13, 2004

The only problem I have had with fumes is when the head pipe came off the flange. I had to drive a couple hundred miles before I could fix it.

You're right though, you might get fumes in the truck if you use turndowns on an SUV. I haven't heard of anyone else on here using turndowns for anything else besides a truck. You could always get a huge lift and then go with a straight-pipe system and not even have to worry about the bending over the axle.

My buddy did a true-dual exhaust on his Sierra Z85 and it looks and sounds pretty good. You could always try and do that, but it will cost you a lot more than just some basic turndowns.\

Good luck with whatever you do.

vanillagorilla · April 16, 2004

Don't go with turn downs. For the reason stated above, and the fact that you mentioned you don't want your exhaust to be obnoxious. Turndowns reverberate off the asphalt and tend to resonate your SUV. Trucks can get away with it, but for cars and SUV's it causes what I like to call the "acoustic guitar effect". Catch my drift. Good luck!

speedshifter · April 16, 2004

Man, if gibson just came out with an extreme dual exhaust version for my truck already, i would be a happy camper. They make an awesome exhuast and they are easy to install. Plus they have a good warranty. My cousin broke a baffle in his muffler (defective muffler) and they sent him an enitrely new exhaust for only what the shipping cost was. You cant beat that.

Butch 02 Denali · April 16, 2004

I also gotta finda a dual in/dual out 2.5" muffler. THe flowmaster SUV 50 series only comes in 2.25" dual in/dual out.

The dual inlet/outlet Flow is easy, any good performance muffler shop can do it for you. I've had many modified. Flows are designed to be easily modified. See the bump-out marked "Inlet" on any single inlet muffler? Flowmaster designed that to add another inlet pipe to. You could get either of these mufflers and do what you need. I don't have the part #'s but I could look them up in my Flow catalog tonight if you want them.

1) get the 2.25 dual in/out and have the muffler shop expand them to 2.5"

2) get a dual out 2.5 with a single in 2.5 and add another 2.5 inlet

Butch 02 Sierra Denali

speedshifter · April 16, 2004

Thanks butch! Didn't think about those ideas. But if I can't do turn downs, I'm prolly just gonna buy a cat back. I'm trying to think of a way to keep the exhuast from goin over the axle and out the back. I was thinking about going w/the dual in/dual out muffler right after the flange, and then having each pipe turn out to the side and exit in front of the rear tires. Probs with that are the left pipe has to go around the driveshaft somehow (more bends ) and the frame rails get in the way so I'd be reducing my ground clearance by a lot if i had the pipes go under the frame rails.

Yeah ive seen a modded flow before, my truck has one now. Except its a offset in/offset out 2.25" flow 40 series. The ghetto muffler shop that the prev owner had do the exhaust butchered up the muffler w/ dual ins/dual outs and this tiny muffler wasn't meant to handle a V-8. But it sounds good

Any ideas on the custom exhaust?

Butch 02 Denali · April 16, 2004

Pretty tough to get the drivers side pipe out like you mentioned. I saw one guy that took 3" tubing and flattened it down to a 1-1.5" oval to go under the driveshaft and frame rail. It actually came out pretty slick looking but it was very hard to make without colapsing the pipe and reducing the cross section area. He made it in sections and welded it together. That was on a 33 Ford street rod but would work on a truck. Way too much work IMO. Not allot of options unless you bring them both out the pass side. I usually start with a 40 series Big block series because the internal ports are much larger, but it will be loud!

Butch 02 Sierra Denali

DrFock352 · April 18, 2004

I just did a real simple exhaust. cut off the stock muffler and welded on a dynomax superturbo with a single 3" out exiting in front of my passenger side rear tire. 260 dollars installed.

speedshifter · April 19, 2004

ok, I'm working up one last idea. I actually went under the truck and took measurements this time.

I was thinking of using an H-pipe and two flow Super 40s (their new muffler), but i dont think i have enuf room to fit both mufflers down there. I was looking at something and the H-pipe kit comes with a pipe that bends and is meant to clear the driveshaft and a straight pipe. As you can see in this pic:

I was gonna use the straight crossover pipe for my h-pipe setup and use the driveshaft one to clear the driveshaft for my left side pipe

If I can fit both mufflers, I can use that crossover pipe for the drivers side exit pipe to clear the driveshaft. My only other probs would be:

1. drivers pipe is running under, and very close to the gas tank

2. I would have to remount my parking brake cables about an inch or two higher on the drivers side so they wouldnt be too close to the pipe when it exits by the frame

The parking brake cable issue is an easy fix. I was thinking about using this on the drivers pipe when it goes under the gas tank:

Thermo-Tec Clamp-on Heat Shield

I took a few pictures that I'll put up on my site and maybe you can get a better picture of my situation from those. You can tell from the pics my ideas on how to get around goin under the frame and stuff.

Later

Butch 02 Denali · April 19, 2004

The plastic gas tank is by far the biggest problem. I don't know what is a safe and legal distance to it for an exhaust pipe. Fitting 2 mufflers is easy, you stand them up, side by side. An "X" pipe is far superior to a "H" pipe and will get you back most of the low end torque you will lose going to the duals.

Butch 02 Sierra Denali

speedshifter · April 19, 2004

yeah problem with the x-pipe is that I have to make bends in the piping to use it. I was trying to keep this exhuast "simple". By simple I mean doing it myself with my truck on a lift and a mig in my hand.

As far as torque loss goes, do you think that I would have better low end if I did a 2.5"dual in, 3" single out type setup? That wouldn't be as cool as the duals, but it would be cheaper to do and soooo much easier to fab. Not to mention I wouldn't even have to deal with the tank, driveshaft, or parking brake cables on the left side

I had a bad experience with my last car and exhuast shops, so I'd rather buy pre-bent mandrel piping and piece the system together myself and weld it all together. Plus none of the shops around here do mandrel bending.

I measured where the muffler is on my truck (don't know if its in stock location or not) but I only have about 7 inches of vertical space between the bottom of the frame rail and the support under the floor, so that means my 10" muffler would hang 3" below the frame rail.

My brother has a true dual exhaust on his '99 Escalade with the mufflers stacked vertically, I'll have to check what he has.

As far as the gas tank goes, the plastic tank has a metal skidplate/heat shield on the bottom of it and that pipe would have that clamp on heat shield on top of it, so in theory very little head would get to the tank.

Okay pics are up: Exhaust Pics

You can see why I want to get rid of the exhaust I got

Since the pipes will be shooting out right before the tire, I don't see any practical way how this could get fumes in the truck? (besides if I am stopped and the rear windows are rolled down the enitre 3" that they go