My buddy has me looking-up and installing a new exhaust system for his truck. He just purchased an 2008 Dakota ST 3.7L, He's looking to spend around $300 in this system. Has anyone else replaced the stock exhaust on a 3.7L? Just wondering if it's practical fo just replace the muffler and add an extension pipe and leave the resonator on or just buy the whole system without a resonator? Would not having a resonator make a 3.7L lose HP or MPG or lack backpresure? I'm set on the flowmaster brand for either a series 50 (Light Truck/SUV) or series 40. Just looking for some suggestions/tips from people that have changed there exhaust.

 

Personally I would cut out the resonator and weld in (or have welded in) a straight section of pipe, then replace the stock muffler with a good flowing muffler like a magnaflow, cherry bomb, dynomax, etc...

 

my main concern is not having a resonator and would mess up his MPG or reduce backpressure or HP... I'm able to weld on a piece of pipe in gettinf rid of the resonator.

 

You shouldn't have to worry about messing up the mpg's or hp when it comes to the resonator. The resonator or resonators (I had two on my truck) are there to help the muffler to reduce exhaust noise. They are free flowing. It really comes to personal preference to remove it or not. I put a flowmaster 50 and kept the front resonator on then a month later I took it off to make the muffler louder. Well it definately made it louder and it sounded great on the outside but the drone on the inside was terrible. Flowmasters tend to have more in cab drone. I went ahead and put the resonator back on and I can hear it in the cab but it's not annoying and it sounds good on the outside. My mpg's, torque, etc. never changed.

In the near future, I'm going to put a magnaflow or some other free flowing muffler on and get rid of the flowmaster. Flowmasters have too much restriction compared to the free flow mufflers.

 

If you do an exhaust some will recommend you replace the Y pipe with one a little more flowing.