MPG's Lost, Gained?

[Screwlywood]

I'm looking really hard at getting some Calspeed longtube headers and a Texas Speed and Performance 224 Cam with 112ls and a custom tune for my 08 5.3l Silverado. I am asking this question because as much as I would enjoy the power gain I am concerened about the mpg loss because I do drive my truck long distances. I have a 44g race fuel cell i will be installing one day but that looks to be ways off. My current setup is K&N cold air intake, magnaflow dumped exaust, 4.10s rolling 35x12.50r17 and an edge programmer. Any thoughts or estimates would be great. I am currently getting around 13-14 reguardless. On the highway if I sit in the draft of another truck it does jump to 16-18.

[RS/SS 4.8]

i lost 3 mpg putting a tsp 220 in mine but i need gears and it should go up by alittle. Botlfed was gettin 21 with his setup i belive and it was modded more agressively than ours.

[kerrige]

With a good tune it might improve.

[03whitez71]

Take off the 35x12.50 tires

[Screwlywood]

Thanks for the info, I am surprised to hear that I could be gaining mpgs with a good tune. I was thinking the tune would also push the mpgs down because of the cam and getting a good air fuel mix. I was thinking the long tubes would help regain some mpgs. The 35s will be coming off one day to be replaced with 37x13.50s. I'm sure it sounds dumb to worry about this as I keep moving farther away but it does ring through when I take long trips in it.

[2k5Squirrel]

Just got my truck tuned last Wednesday. Picked up 3 mpg...even loaded down with 5 days worth the camping supplies!

I went from 13.1 to 16.1 mpg!

[canada4g63]

That is a very good pic up in mpg's

[Duct_tape123]

I'm was getting 15-16 city with stock cam, longtubes, circle D trail blazer converter, 4.10s, 265/75/16(about 32"), and a SWG tune. I just swapped a 222/224 112 cam and city dropped considerably, but I'm still dogging on it hard. Highway mileage hasn't changed, I can still get 18-19. I think if I throw some p&p heads with flat top pistons and up my DCR it will improve mileage.