Thrush Muffler Question

For any of you guys that have upgraded or replaced your stock muffler with the Thrush welded muffler, or any off the shelf aftermarket muffler, what offset(s) did you purchase? My stock muffler has split down the seem and I need to replace it. After reading some threads on TW it seems many are more than satisfied with their thrush welded mufflers and how could you beat the price? Worst case I'm out 40 bucks. I went and purchased one today from my local advance auto but after looking at it I'm not sure its going to work. I wasn't even thinking and just purchase whichever one it recommended for my year, make, model . I wanted to be as sure as possible before cutting out my stock muffler. FWIW after getting it home and inspecting it, the muffler I purchased is offset inlet and centered outlet I believe. Any help and/or pictures of your setup would be greatly appreciated.

 

anything will fit if you have a welder. Typically the inlet is centered and the outlet is offset but it should say for sure on the box. It may even be reversible

 

Yeah I know a muffler shop can make almost anything work but I've also seen some of the "work" that comes out of those shops hahaha. I know the pipe size is 2-1/4" but I was trying to figure out what configuration (inlet and outlet positions) to make it best and most easily with the existing tailpipe and so on.

With that being said, this afternoon I cut my stock muffler out of the truck. I figured out that the inlet is lower than the outlet but they both seem to be on verticle plane with each other. I haven't put my new thrush in yet but I'm almost positive it's going to work in a verticle position. I held in it position and it seems as if there enough room about the exhaust to have the inlet offset to the bottom and the outlet centered. I will be welding it all in tomorrow most likely.

 

Yep, if you want to be 100% you can measure the vertical distance between the center of the in/outlet of the OEM muffler. I'm guessing the Thrush will be very close if not the same but you have a lot more flexibility when you have a welder. Don't forget to double check that the muffler is reversible, some of them are single direction and would probably sound hella strange if installed backwards

 

I shouldn't need it to go backwards but I looked at it like 10 times to make sure I was reading it right when it had "outlet" stamped on the end that was centered. I expected the inlet to be center and the outlet to offset but I guess I was wrong. It's actually kinda nice the way it is because now the muffler won't hang down anymore than absolutely necessary.

 

Any troubles welding it in? I'm going to do mine tomorrow and can't decide if I'm gonna drop it or try to weld in place

 

So here's the deal got it all welded up and I meant to take pictures to post but I will take some in daylight tomorrow. Since a few months ago the flange between the cat and the downstream O2 sensor setting a check engine code off. When I figured it out and took it to the exhaust shop they just cut the flange out and welded in a piece of pipe. Wasn't real thrilled about that one but it made dropping the front part of the exhaust nearly impossible.

What I did was remove the tailpipe and welded the muffler in a totally verticle position on the tailpipe outside of the truck. Obviously I got it mocked up under the truck. Then I had to drop the spare tire to make it easy getting back in over the rear axle. Welding in the portion forward of the muffler wasn't very fun although it was only one weld. I should also mention I had my driveshaft out at the driveline shop getting rebalanced so that gave me a decent amount of extra room but still not enough to get on top really well. I would advise dropping the whole thing if feasible because it would make welding much easier.

Overall it was a good learning experience. I like the outside sound of the thrush but I'm not excited about the large increase of noise in the cab. Hopefully it will grow on me. I still haven't gotten it on the highway yet as the noise seems to change greatly through the rpm range so maybe on the highway it won't be so bad. Good luck wulf. I'll get some pics up tomorrow.

 

What exactly do you mean by "turn it down?" You mean physically turn it down from being verticle or putting a downturn pipe on it? If it's the latter I used the stock tailpipe.

 

I know this but you said it as a verb like it was something I was suppose to do. As I said before I utilized the stock tailpipe and it honestly sounds almost like I'm running no muffler that dumps right after the cab

 

These are the pictures of how I mounted the muffler. Excuse the jack and jack stands. I was taking my rear wheels off as I'm in the process of painting my wheels gunmetal.

 

How did you make out doing yours?

 

It was a huge pita. I couldn't unbolt the catback and couldn't figure out how to cut the inner bolt off so I cut the pipe right before the muffler and fished the whole thing out.

I welded the new muffler to the tailpipe and weaved the whole thing in, then welded up the front.

The most disappointing thing is that it's only really audible if I break 3k RPM in 1st. I don't have a Thrush though, it's a Holley Flowtech Terminator. I had to run to the hardware store after I cut off the muffler and it sounded better besides being too loud, so I might hack it off and go with a glasspack.

 

Well in this case I wish we were opposite. My thrush makes lots of noise. Sounds great outside the truck but it's too loud inside. Most of the noise is recognizeable around the 2000-2500 rpm range. Once you get up to about 3000 a lot of the rumble is lost and it's more flatline

 

hmmmm, that's a bummer, I've heard that the Thrush is probably the best sounding muffler for these trucks... you could try and add a glass pack in front of it to act as a resonator.

After driving more yesterday when cruising I can't really hear mine over the KM2s which are pretty loud, but it is audible on heavy acceleration. Not quite the result I hoped for but it's better than being too loud I suppose.