Any body swapped out the factory q-jet manifold with and aftermarket one and noticed a difference? I currently have a factory aluminum one from a mid eigthies truck. I am using it on a 350 with a 270HR comp cam and 305 HO (416) heads. I don't want to waste the time and money for say only 5 horsepower or so.

 

On a near-stock engine I'd say it's worth more like 10, but nothing to write home about. Then again, you can pick up a used Performer intake for next to nothing used so it's till a good bang-for-the-buck modification.