I have a question regaurding the flowmaster 40 series 3"inlet dual 2.5" outlet muffler. If I'm not wrong then my 98' 1500 has a 3" pipe coming from the cat to the muffler. Would this muffler just slide onto the cat pipe or would I need some kind of connector or something.?

Thanks,
Mike.

 

The flowmaster is going to be shorter so you will have to add a piece of pipe. Flows also have to be welded.

 

Actaully I was wrong, the cat pipe is 2.5", would I have to get a 2.5" inlet then, this may sound stupid but I dont know because when i measured my stock muffler it was a 2.75" inlet so I'm a little confused. Or is it just that if you buy a 2.5" the muffler will actually be 2.75 to fit over the 2.5" cat pipe. And I'm not planning on extending it because I'm just gonna dump it after the muffler.


What I'm trying to figure out is will this work.

http://cgi.ebay.com/ebaymotors/ws/eB...category=33636

Its the 2.5" inlet and I want to know if it will slide onto the cat pipe?
Mike.

 

I don't know much about them but I sure that a mufler shop can make it work. If not and it is still in the box, maybe they would trade for the correct one.

 

I just did the swap you want on my truck yesterday. The muffler you want is indeed 2.5" inlet. You can use a 3' if you cut the piping closer to the cats and also closer to the tailpipe where it is 3", but the stock piping narrows right before the muffler. My shop bolted a 40 series flowmaster with 2.5" in and out onto my truck in 30 minutes... fit perfectly.

PS. The muffler you are looking at is identical to the one I just installed except that mine is #42543 (Offset/Offset).

 

correct me if im wrong but thats fine... that is for so you can over lap the pipe... just make a nice tight weld right around the connection and you will be set.... any muffler shop should be able to do that for you with no problem

 

My american thunder dual kit from flowmaster came with a 2 1/2" to 3' adapter. I would think any good muffler shop would those availiable.

 

Well, I'm still in school, and I was going to do this myself(say the $$$), I figured that I would try without welding first, and if it leaks, my friends dad welds so I have him help me out. But ya, your saying that if I cut that pipe I can fit a 3" in? What would you do, 2.5 in/outlet or 3" in and dual out 2.5". Because ya I checked what the american thunder has and it comes with that adaptor. Can you get that thing anywhere? Also, which was is the best to mount a muffler, vertically or horizontally, or does it really not make any difference how its mounted.

Mike.

 

You might have trouble doing this yourself. The muffler is not a direct fit, so the shop has to do a small amount of bending on a piece of pipe to make up for the length difference between the flow and the stock muff. Also you want to add some hangers to support the muff and pipe. Seeing as you have only one muff you would generally want to mount it horizontally or on a slight angle, generally only dual muffs mounted side by side mount vertically. I see everyone with single in, dual stright outs so I wanted to maintain slightly stock look, so I went with 2.5 rather than 3 to maintain backpressure for my low end. Ultimately If I were you and you have not done this kind of thing before, buy the muff online to save close to 100 bucks, then get a shop to do a quick install. Mine took half n hour or so, and minus the muffler cost me about 100 CDN buks for labour, the new pipe, other misc shop stuff and tax.

 

I used to work a Oreilly auto parts and they had the adapter on the shelve out front in the store. If i remember right it should be pretty cheap like less than ten bucks. They should have all the muffler clamps that u need also for a good price. U might look into having the muffler clamps welded where the bolts go on as it is common for the to come loose and fall of after a while. or just use high temp lock tite but if u have a friend that can weld them it will save u some money there. good luck.