Originally Posted by Old man with a Hemi2

08....15-18 rwhp would be noticeable in the seat of your pants, and when I did my Flex-a-lite 180 years ago, was expecting just that, but felt absolutely nothing at all. I'm sure they're good for a few extra hp, but not what is advertised. The best bang for your buck performance mod is gears, always has been, always will be, and actually can achieve a mpg improvement at the same time, if your vehicle was geared wrong for conditions it faces ie oversize tires