I just bought a 2008 Tacoma Prerunner, V6, SR5, Off Road, 20k. Procomp 6'lift with 35" tires, magnaflow exhaust.

I have been reading a lot of info on lifted Tacomas and the mpg ranges from 14 to 20, however I am averaging 9mpg city and 15mpg highway. Anyone have some suggestions as to why this might be?

In addition I have been hearing a noise from the engine that almost sounds like an exhaust manifold leak but have been unable to find it.

Also when driving uphill under low toque, and not pushing the engine, as certain speeds it starts to sound like I'm driving a diesel engine.

Dealer has told me that these are all "normal" things for this truck but I am having a hard time believing this after reading everyone’s comments on these trucks.

I love the truck but am just frustrated by this few issues.

when you compute the millage, gotta ask did you throw in the error for the big tires?
sitting that tall with bigger tires you gas millage is going to be bad
and engine is going to be working hard at highway speed with the gearing difference of the tires and the aero package of a barn door.

you have a megaflow muffler have you checked the exhaust for leaks?
still have the cats on it? if answer is no then you have changed the torque curve for your engine

The loss in gas mileage might be due to the tires. I noticed a drop myself when I changed from the stock Rugged Trails to Mud Terrain KM2s, and that's still with stock suspension.

No exhaust leaks that I can find. As for the difference in speedo i took that into concideration, was my first thought. Even still I have seen alot of posts on here from people with the same setup gettin 16ish mpg

The loss in gas mileage might be due to the tires. I noticed a drop myself when I changed from the stock Rugged Trails to Mud Terrain KM2s, and that's still with stock suspension.

That could be some of it.... I need to look into different tire and tread patterns, maybe something a little less aggressive

if you still have a stock spare, weigh it, then weigh one of your 35 in tires
that is all rolling mass that requires horsepower to turn

and upgraded breaks to stop