I have an LT1 in my K5 and just finished swapping it in but my combo of 33 inch tires and 3:08 gear ratio = my truck going no where and almost stalling every stop light. I'm swapping in a 4:10 or 4:56 ratio but how important is it to program my PCM after I do this swap?

 

Ryan I'll move this over to LT1 Tech since this doesnt really fit this forum.

Brook had the right idea above about the speedo and tach being off.

Also checkout Advanced Tech Posting Guidelines If you have time.

Thanks,
Ken