Seeing as I have a Camper Special w/dual gas tanks, its hard to run a true dual exhaust under it (not much room). I had a "Y" pipe put on to run a single inlet/dual outlet system. I also put a walker glasspack on it. Still not happy with the sound. Nice idle, but, NO sound on acceleration. Stock almost sounds better.

Questions:
1.) Exhaust size: The stock exhaust is 2.5" inlet/2" outlet. I have been reading about the back-pressure/low end grunt issues on this forum. Still somewhat confused. If I go to a 2.5" outlet muffler vs. the stock 2" outlet....will that hurt my back-pressure/low end torque....or should I stay with the 2". It just seems like a very small outlet for a big motor. Plus, the 2.5" may sound better too?? Just don't want to lose torque.

2.) Muffler: Also, looking for advice on a good sounding muffler, but am hesitant to go to a Flowmaster, or Magnaflow. Would like to find something that brings out the natural smooth rumble of the 390, but with a little "something" extra to it, but not too much. Example: Something like a heavy duty truck muffler to make it resonate just a little more...throaty without being over-the-top?? I used to have a 360 in a 1970 that had that kind of set-up but its long gone and I didn't do the work.

I will probably just go back to a single exhaust outlet. But, just curious about the diameter outlet issue and best muffler. If anybody has faced these quandries, I'd like to hear how you solved them.

Thanks guys!

Dave

 

Well i would stick with one size for in out like 2.25 all the way through or 2.5 is more than adequate you could go 3 in single though not dual its possible to go dual just run both pipes on passenger then exit wherever you please

But ill tell you flowmaster sounds really aggresive mean tone and you can hear it in the cab i can i like em i have em on my truck i dont have a clip many people go for glasspacks but they might be too loud for your tastes there more raspy snappy magnaflow arent that loud i dont think anyway but good luck with your decision

 

I am thinking of going with 2.50 in and 2.50 out. Just not sure why they had the small 2.00" outlet on the stock exhaust on a truck with a 390 motor. I am sure it had something to do with the low end torque. It looks strange to see that little 2" pipe coming out the sides.


By the way, what Flowmaster muffler are you running? 40 Series, 50 Series or ??? I am strongly considering them, just want to make the right decision. I have read good things about the 50 HD Series ...not too loud, but just right.