I use only 93 octane, and i had it on to different dyno jet dynos and i wish i could get somone with a 08 to dyno there car on one of the two dynos i dyno'd my car on. There is another 2008 viper owner on this web site that dyno'd his 08 and got 522 HP with a KN air filter here is his link
http://www.viperalley.com/forum/vipe...o-numbers.html
My car put out 508 stock and 522 with KN same as his and 547 HP with KN and hennessey exhaust, i am starting to think my car is right on and it's just variable's in dyno's, this guy's car put out the same exact power as mine with KN filter.