I use to run 24 PSI on 1'st and 2'nd then drop to 21 on third with my thrasher and stock turbo/stock injectors. Car ran 12.1's at 110 MPH. Using the SMC kit at that boost level I could only run the 92 without getting KR. If I used the 97 or 100 , I would see KR top of 3rd. But understand stock IC and motor. That was 2 years ago. I tried the 108 as well, but found it knocked like crazy.. that was then.
I have learned over the past few months if your able to really up the flow of alky through the motor.. a lot more timing can be run, as well as a lot more boost. Also have learned that if improvements to airflow and its cooling are done.. alky works especially well. Whereas if the car has a bigger IC, bigger turbo, etc.. it is able to handle a lot more timing at much higher boost levels without KR. This is injecting heavy doses of methanol.
There is a big difference in saying the car runs lets say 25 PSI boost at 830's for O2's and 25 PSI at 710's for O2's. Those that tune their cars at the track know the big MPH and ET difference. Mix timing with low O2's and high EGT's.. you'll cook some really fast times.. whats your level of play..everybody has their personal limits. You have to find out what makes more power at the track. Seat of the pants.. goes so far.
If you can run 26 degrees of timing, at low 700's, and 25+ PSI boost..you have a serious car.. if its not detonating. But to get the higher timing to work..got to work on the overall package. can this be achieved..
Back to the question asked, Paul, for dialing in an alky kit initially, its always better to start with a low timing chip. Whether your car can run a high timing chip or not..cross that bridge in the process of dialing it in. Way too many variables to contend with.
Lastly, I also find cars with better breathing like bigger IC, bigger turbos, cams, heads, etc.. dont work well with the Thrasher chips. Nothing against them, but if you have a special motor, you need a special chip. For a stock long block/stock IC..they are killer. Especially for a drop in and go chip.
Easy on the timing guys.. It can harness power, but can also harness KR. On the track with a cool motor is one thing, on the street with a heat soaked motor..its another.
HTH
Julio