My gas mileage has dropped significantly from 15-16mpg to just over 13 mpg after a Flowmaster 40 series catback install and tire swap to Firestone Destination M/T's(from Wrangler ST's). I added a K&N FIPK to the 5.3 which brought me to high 11's in gas mileage. This is pretty ridiculous. I thought the mods would help gas mileage. The only one that I thought would drop it was the tires. Is this much normal?

 

What size was your previous tires and what size are your currenttires? You would be amazed how increasing the size of tires can decrease your gas mileage.

 

Is your speedo updated/?

 

Hey argon im putting 285 70 r17 tires on this morning and was wondering since they are a little tallerwhats the easiest way to fixthe speedo and trip odometer farely cheap? Thanks

 

Thats a good question...

We'll re-cal it free for a good customer...maybe charge a tad otherwise....around $27.50..

A modern tire store SHOULD be able to change it...but most can not.About all you can do is see what your dealer will charge.Let me know!

 

Hunt, if you decide to go with a Superchip Flashpaq as I did, you can adjust the speedo to the size of tire you have. It is very simple and it works. I had a cop on my base clock me to see if it was correct and it was right on point.

 

Yes those work SC_CHEVY, but that is alot of cost for that. The change is only 3.5 percent, so I just do the math. At 60 you are actually going 62.1 MPH etc.

 

Smoke I wasn't implying that he buys a Flashpaq for the sole purpose of adjusting his speedo. I was simply saying that if got the Flashpaq for "performance" the calibration setting is just an added bonus.

 

but did the flashpac really help much? Seems he would be better off with a custom tune, and get the spedo adjusted then. Also I believe it is cheaper right?

 

Thats was my main question smoke20 was is it even worth it. I had not seen how far off it was so if its only 2 or so miles an hour off im fine. Thanks guys.