SLP is usually conservative on their numbers. I can not speak from experiance, but on the Firehawks they converted, they made rear wheel horsepower at or near what was advertised at the crank. :cool
Maybe this will some help.
well I owned a brand new, 0 miles, manual, stock 04 for 6 months and now I own a used 34K miles, automatic 04 with the slp 421 bobcat kit. it definately pulls alot harder at 5000rpm than the stock one and sounds way better too!
In reference to times for an 05, I have an 06 and competed with 05's and 06's this past friday at VMP. We had the track for the day and the stock cars where running mid 13's. Since it was the first time for me, my best was 14.3 twice.