you can get him to not raise the timing to high on the low octane table. then raise it higher on the high octane table. that way if you want to run 87 you can. the pcm will go to the low octane table.

 

PCM located to the left of the battery if your facing your engine compartment. You will see a plastic cover next to the battery. The PCM is covered by it.
I believe you need to remove your battery and a few brackets to access it or remove it. Not hard.
The dual tune is ok, but not recommended. At least that's what Allen Nelson told me. When you switch from 93oct to 87oct you will get spark knock for a while until the PCM can adjust for it. Though when you go from 87oct to 93oct you will be fine. The PCM will there again take a while to adjust for the higher oct fuel to benifit from timming advance.
Nelson told me he would install the dual tune if I really wanted it, but he said it's not the best tune. Therefore I went with the 93oct tune. Hey it's only about !!!!!! $5.00 !!!!!! more on a 24 gal fill up versus filling up with 87 oct fuel. I don't think you should be driving a truck if 5 bucks is going to make or break you through the week.
Seems logical to me.
Just my 2-Cents.

Jim

 

i got a 93 tune and thats all i run in mine. i agree with chevy6000vho about the 5 dollar part. only thing wrond with nelson is he is to busy to get back to you in a timely manner. i live in georgia and it takes him at least 4 days to get back to me. im not trying to knock him or anything cause his tune killed my diablosport but he needs to hire some help over there. just my opinion

 

There's another post that talks about him hireing a new person. I believe it was supposed to happen this week.

 

What he said