Here's the rundown. 2003 Silverado 2500 HD, extended cab, 4.10's. So far I installed a Vortec 3" in, single 3" out muffler with the stock exhaust pipes, so basically just a muffler. I'm looking mostly for torque & pulling power, I have no intention on bringing this truck to the track. It's a work horse that will be subjected to some pretty heavy ****. What are your suggestions on mods that will help me achieve what I'm looking to do.

Thanks in advance!

 

headers and ls1 edit will help a bunch.

p.s. my hd had 2 3" into 1 muffler and 2 3" out to a yipe and single tail

 

besides the headers and the LS edit. You could go with a mild cam something in the 200-204 degree duration @.050" lift with a 114-116 LSA w/.515-.530 lift. this type of cam in a 6.0L won't lose any low-end but will pick up trq/HP in the pulling range 2400-3600 rpm.

 

Great! Sounds good guys. What about an intake?

 

Nice truck, Probley try a UPD intake predator programmer, today i'm putting on JBA shorty headers. I've been told these make better torque gains rather then HP. If you can wait two days I can tell you the before and after of all my mods.