What happened!? MPG waaaay down.

[navymech4x4]

I was running approx 17 mpg on my 06 Ram 1500 5.7 when it was all stock. I installed a drop in K&N filter and also an exhaust (Cherry bomb extreme single in dual out). Ran it this way for a week and loved it. I purchased the Predator U7137, updated it to 9r13 and installed the 87 octane tune. fuel economy is now at 13 to 13.5 mpg. Any ideas what happened and how i can get it back? The truck is running absolutely different with rpms staying way high during hwy driving and occasionally during around town driving. roughly 19-2000 at 65-70 mph and the tranny constantly downshifts and will never seem to go into overdrive or upshift on hwy cruising to lower the rpms. Any ideas here??

[bighemitex]

any datalogs?

[navymech4x4]

nothing current as of yet. laptop crashed on me. i should have data in a few days though.

[mikel]

did you make any adjustments to the tune?
cruise rpm should not be changed...

[navymech4x4]

no adjustments. i loaded the 89 ECM and TCM tune as is. I am beginning to wonder though if it might be something with the exhaust and not the tune. im going to put the stock exaust back under the truck and see what happens that way with the tune still loaded.