upgrade cylinder heads

i have a 2001 stock 5.3L silverado.. i wana know wha is a good cylinder head repalcement or modification to get more horse power.. any suggestions are welcome

i have a 2001 stock 5.3L silverado.. i wana know wha is a good cylinder head repalcement or modification to get more horse power.. any suggestions are welcome

so you have two 01 silverados. This one is stock and the other one has exhaust intake and heads with programmer? And junk throttle body spacer.
How about changing your cam. Or your rear end.

The stock heads really aren't that bad for flow. The cam idea might be worth investigating.