I had Arrington bore and stroke my 6.1L to 7.2L and left it N/A. Kit was advertised as 600hp N/A, and it did dyno at 525rwhp. Saved the cost of the super-charger. Next time will go 7.0L with Super-Charger for around 800hp. This is in my 6spd Challenger daily driver, and it still gets 19mpg at 70mph. Can smack down a lot of expensive imports now!