Originally posted by leochevy2001@Sep 11 2003, 11:32 AM
Why does the 03 LM7 5.3 have 10 more hp than the 00-02 and 5 more hp than the LM4 5.3? What all was changed from 00-02 to 03? Why would GM make two 2003 5.3L motors and have one with more hp than the other and the same amount of torque? How do you know that you are getting a LM4 or LM7?
99 had 270hp
00 had 285hp
01 had 285hp
02 had 285hp
03 had 285hp
04 had 290hp I think

99 had a different cam than the 00-02's.

The '03 probably have a different cam again or a few degrees of timing added.

GM is stupid. Just get any used 5.3 and throw a 6.0 cam in there...you can get it probably for free and will make about 20 more hp than a 99 and about another 10 than the 00-03