L31MaxExpress
I'm Awesome
I implied a tune with the mention of the 0411 swap. Factory 0411 itself even if you merely deleted the VATS and installed it with the factory L30 van tune will give a little better MPG. The other added benifit is the 0411 can easily control electric fans. Electrc fans run only when needed so that helps MPG.I know the 0411 swap has been mentioned, but I haven't seen anyone recommend a tune yet which is surprising.
While I did them for power, the March Underdrive pulleys and 1.6 roller rockers gave my 350 a little better mileage too. Every bit of power loss recovered from reducing friction helps mileage.
I used synthetic gear oil in the rear-end, synthetic wheel bearing grease when I did the front brakes, and used synthetic caliper grease on the slide pins to help keep them moving freely. Also replaced the calipers and all 3 brake hoses. I had a caliper sticking and just shot gunned the front brakes because I used the larger 8800 GVW calipers for better stopping.