Hey guys, my current muffler has rust and erosion holes in it and it is now very noisy and killing my gas mileage. My questions is, when I buy a new muffler can I simply take the old one off and replace it with the new one? Is there any welding or sodering that has to be done? Sorry for the stupid question & thanks in advance for all your help!!

If you get a OE replacement axle back, you should be able to just take the old one off, and put the new one on. You'll need a new gasket, and probably need new bolts (SS bolts from the hardware store are what I'd recommend) since the old ones are probably going to be rusted fast, and need to be cut off.

If your muffler is not welded use a chisel to cut muffler off of pipes. Do this by cutting the muffler inlet and outlet tubes on both sides. Once the inlet and outlet tubes are free, you can now remove the muffler.

 

Since most mufflers have an inlet and outlet end, make sure they are pointed in the right direction.

How is a hole in your muffler killing your gas mileage? Mufflers are flow restrictions that create pumping losses.

 

I've heard of low backpressure killing torque, but not fuel economy.

 

You should also consider the option of rigging up a cheap muffler. AutoZone sells a 2.25" inlet /2.25" outlet 13" canister for $15. Add some strapping, a few clamps, and a 18" length of pipe so you clear the bumper, and you've got an ugly, noisy, adequate muffler for $25. Guaranteed to rust out in three years or your money back.