Originally Posted by metalguysteveo
5.E3 Diamond Fire spark plugs.Claims to increase hp up to 12%.Thats about the best bang for your buck imo seeing how they are only $5.99 each.I already have performance wires but i will be upgrading again with these new plugs.
6.Underdrive pulleys.Claim to increase up to 24% hp.I havent yet found a company that sells more than just the harmonic balancer underdrive pulley but this one alone claims up to 9hp increase.
Don't expect any performance increase from higher temp plugs, let alone 12%(that's BS). They DO NOT add HPs, they only have a more efficient burn in the chamber, which may result in a few HPs, ubt most common is a cleaner cylinder for longevity of the motor.
As for underdrive pulleys, documented off of a 2006 5.7L HEMI, a 20% underdrive pulley added 8HP and 7.5ft-lbs of torque; so claims of 24% is utterly unrealistic.