The problem with the stock setup is the very restrictive muffler. It doesnt look like you are after big power and flow. I would just chop out the muffler and add a
4-inch FTE resonator and call it good. If you decide to upgrade you can still use the resonator. Cheap and I bet it will get you what you need.

 

I paid $240 for my 4" Diamond eye 5 years ago and it's still holding up fine.

 

I am a Magnaflow kind of guy. Don't recall the price but I know it was not the least expensive. However the fit was perfect ad the system came with all of the correct pieces for any configuration, you just wind up with some spares to play with.

 

It's not that different sounding. The engine clatter is still far noisier than 4" straight unless you're really womping on it. I would maybe try what DMD suggested and ditch the stock muffler for a piece of straight pipe or a straight through resonator. That is probably where most of the gains come from by getting rid of the entire stock exhaust. Getting rid of the EBPV also helps a little.

 

Straight piped is considerably louder. Not as loud as a straight piped gasser, but still loud. Possibly more noticeable outside, but still quite noticeable inside, and more so in an Excursion than a pickup.

Many have argued that the DP is where the gains are and that the stock muffler is fine to 400HP. From my wee bit of testing, the stock muffler appears to be slightly restrictive even at stock power, and more so with a tune. Haven't done a before/after test on a DP.

 

Yea I am probably going to go with the Diamond exhaust from above. Also going to purchase a black exhaust tip 4" inlet and 5" outlet. Nothing too big. Figured 5" should be ideal.

 

I have a 4" MBRP with the 5" polished tip at the end and think it looks good. Like you said, ideal size for a truck like ours.

Diamond makes a nice product, let us know what you think of it once installed.

 

My son "straight piped" his '02 7.3 by simply cutting off the stock muffler. He liked it, but being the old fart I am, I thought it sounded like a diesel ricer fart can myself and was obnoxious throughout our neighborhood just because of the many hills to get up and down in/out of the subdivision. It sounded nasty to me (nasty being used here as a negative term).

 

I transferred the S&B cold air intake (#75-5062) off my '01 that got squashed and went with the MBRP 4" turbo back straight pipe. I guess the long bed moves the noise back enough that it isn't bad in the cab. Not real sure about performance gains but the EGT did drop. A shop did the install and instead of the clamps that came with the system they welded the pipes together.