I think that it has more to do with the program you load into your truck than it does with how its created(EFI live, store bought comercial downloader, harness box like the juice) etc. This is the main reason that I moved this post IMO its not realy an EFI live question......unless you are looking for tips on tuning around the need for a shim? In witch case I can move it back to the EFI live forum and the discussion can steer that direction.
Make the program you chose. If you dont get codes then dont worry about it. If you get codes then look into what the best way is to correct not getting them. So I would say......wait to make the decision if you want to shim the truck. JMO
Here is a pretty good recent post about when/if they are needed etc.http://www.dieselplace.com/forum/showthread.php?t=126478
There is also some prety deccent reccent discussion about the fule system in general in posts about aftermarket fuel pick ups and lift pumps. Brows through the first couple pages.....good reccent reading
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