4.8 spun a rod bearing so time for a new engine. Im wanting to go with a 6.0 or at the very least a 5.3, but Im still looking to get halfway decent fuel economy. Truck is a regular cab 2 wheel drive. It already has a built 4l60e, longtube headers and a decent tune. Ill keep the 4l60 trans for sure. By swapping to a 6.0 lq4 or lq9 will I really see a detrimental decrease in fuel economy. I drive mostly highway and dont flog on it except for when I go to the track. Right now its averaging about 17-18 on the highway. I was wanting to do a 6.0 with a mild cam(texas speed 224) and I also have a tbss intake sitting in the garage at the house. Ive searched a lot and found inconclusive evidence. Just want some decent opinions from those who have done it.