I made the following mods: 2 inch front leveling kit, went from 265/65/18s to 285/65/18s, single in/ dual out flowmaster exhaust system.


My mpg went from 16 stock to 14 with mods. Is there anything I can do to improve mpg?

2008 5.3L Silverado crewcab

 

Well the exhaust will have made the most difference. That's about how much mine dropped when I stuck on my single in/dual out Flowmaster 40. Only mine dropped from like 18-19 to 15-16. The leveling kit and bigger tires are also allowing more air to go underneath the truck which is reducing its aerodynamic properties. Obviously as truckers know, less aerodynamics = less fuel economy at highway speeds. If you haven't done an intake that would be the thing to do at this point. It will help a little bit as long as you stay out of the throttle. Atleast do a K&N drop in air filter(bout $50) and read up on the red neck ram air mod. Considering your truck is still under warranty you probably don't want to be modifying the factory air box but the alternative is a $200 air intake kit from Airaid or K&N on www.summitracing.com

Good luck

 

The Single in dual out catback system won't get you worse mileage, its that thing that yer shoe is attached to, pushin down on the throttle to hear it BAAAAAARRRRRK, or BLATTTTTTTTTTTTT that causes less MPG i think, been there, still doin that too, with my new exhaust from last fall. Flowmaster 50 series with single in, dual out the back.

 

Coud have been crapy gas. I run 93 now and I gained more MPG's

 

Wrong. Sorry Jim. I drove my truck out of town to get a stump grinder I own fixed. While I was at the other city I decided I wanted to go ahead and get my exhaust done while I waited on my stump grinder to get fixed. 50 miles both ways. Going, running about 75 I was getting something like 19mpg on the level spots. Coming back with the exhaust doneI was getting 17mpg on the level spots (the terrain is mostly up, down, up, down, here.) And that's how my mpg has been ever since then.

 

Psh... you guys don't know what hills are. Up and down and up and down to you probably means veritable ice rink flatness to me.

I wonder what made the early settlers decide to build the city of Seattle on a bunch of fackin hills?