[Jay S]

Originally Posted by AG

For me it's a decision between extracting every hp possible or sacrificing some hp for the stock look of RA manifolds. I have about a 415 hp 455 in my '72 LeMans right now with RA manifolds and will start on a 600 hp 494 ci motor soon to replace it. I'm struggling with should I use RP RA manifolds or headers? I have both, but I don't really want to move my brake lines and metering block that's on the frame in the way for headers. It's a 50/50 right now, but I'll probably end up with RA manifolds (2.5") since I'll never race the car.

Where that already has the RA manifolds with the down pipe and full exhaust, I can’t blame you for keeping with them. As long as it has the correct mix of parts, like a dual plane intake and the cam to match, there is no reason to use headers. But starting from scratch buying parts and a stock look is really not a goal with close to 600HP, my car would get headers.

That engine Morris had on the dyno loosing about 40 lbs of torque at 3700 was showing a bad mix of parts someplace with the RA manifolds, the headers solved it. Which would be easy to overcome, but running that engine as it is with the RA manifolds would not have been very ideal at all.