I want to see what Ox says too, but I'd say around 12.85-12.95....

 

While I have driven a few 4.8's I have yet to mod one. I would have to say all things being equal the difference would be around 3-4 tenths. It could be closer with more specific tuning. Had I gone 4.8 I would be interested in extending my RPM range 6200-6400 (I'm not sure how far you could push the stock components) and a larger converter (3600-3800). I would have probably considered the swap from a truck to LS6 manifold as well and maybe a cam too. I know this doesn't make for a direct comparision but this is where I think the 4.8 needs to steer to to make power.

A larger shot and better suspension could put a 4.8 easily on the same mark as my 5.3...but consideration for longevity is a must on a street vehicle.

Richard