06 Freightliner C-13 muffler

I can't imagine why you got no replies. Go to your local parts house and buy or order a Donaldson 100463 muffler. This is the same one that PP and PDI sell as their private brand performance muffler at a 50% plus markup. The catalytic muffler is a restrictive nightmare. Assuming you have a Columbia or Century also add a Fleet air filter and you'll pick up 35-40hp and at least 3/10ths on the fuel mileage. I have a C13 that the mufflers didn't help much because they are so weak with the factory tunes.I got a 500/1750 European tune put in and went from 4.8 to nearly 7mpg. ROBSREDFORD or Mr Haney can tune you up if you decide this is for you. I think this is mostly because the engine is no longer running balls out all the time.

 

I agree the factory muffler/converter is killing your performance and economy. The Donaldson 463 will help a bunch, so will a Walker Mega-Flow but its a little louder but they are both a bunch cheaper than the factory replacement. Also they are 10" diameter mufflers but even with new mounting clamps/brackets your still going to only spend about 300.00 (parts only, you'll have to pay for labor if you are not going to do it yourself)compared to the 4K you were quoted for a factory replacement.