I've heard that now a days theres no need to tie into OEM harnesses to install remote starters. My question is if there is a good alarm/starter combo that is plug and play? Specifically for my 2008 Sierra Denali?

 

your Denali should already have remote start on it, well mine came factory installed with it anyhow

 

98 99 01 02 03 04 05 06 07 CHEVY SILVERADO REMOTE START - eBay (item 400227749697 end time Oct-04-11 17:23:18 PDT)



This what I found for the older bodies

 

Your 08 Denali has factory remote start, just have to go to the dealership and get it programmed and remotes.