hotstang46

Plain and simple, how much HP are the factory high performance gils costing me? They are one of the only parts I re used from the 454 mags I pulled out at the urging of a few people saying not worth the upgrade to another manifold as they are a decent piece. Just built two fresh 540's, NA that are producing about 700hp per side on the engine dyno with their dyno headers. I just can't seem to get a solid answer. Engine builder thinks probably not much, maybe 20hp vs a higher performance header, but that was just a guess. If it's a big spread I think I'd like some EMI Thunders.

Thanks Guys!

f311fr1

The Gils are fine. Look at the Lighting header web site,they used to have some dyno comparisons

DiamondPerformance

iTrader: (2)

This graph was done by Fountain.

hotstang46

Exactly what I needed, thank you so much!

Griff

On an NA 540 700 hp engine I'd guess the Gils make 30-50hp less.