To reset the computer just unplug the battery for about 1/2 an hour. Learned this from a different thread on here. Glad I did... immediate difference. The VX RAN differently on the highway. The motor was actually quieter and smoother...

As for the muffler...
After I tried the Flowmaster Super40 and loved the sound but hated the MPG, torque loss, etc... I went with a Cherry Bomb Vortex. This is very similar internally to the Flowmaster, with an added element... glass packed innerds!
Noise level... if the Flowmaster was a 10 at it's loudest, the Vortex is a 7.
Performance/Torque... Stock is a 10, Flowmaster is a 5, and the Vortex is a 9! Barely any loss. (Rephrase... barely any loss now that the computer is reset!)
MPG... Stock I had max range of 370 miles. Flowmaster, around 327. Vortex... 411. BUT, before I did the computer reset, the Vortex had 327ish too... So, it's very possible that the Flowmaster could have been better if I had known about the reset trick back then.

Also note... I'm NOT a Grandpa on the road either...
AND, this is the 3rd week in a row that I've had mileage in the 400 range.

Now... before I get too excited. Could someone tell me the variance to multiply by for 255-55-18 tires?
Being that these are wider than stock and not taller (by much) I don't see the numbers changing too much. Could be wrong...

Thank you!