Slant Six Won't Rev over 3500 RPM

Throttle opens all the way. The engine will rev higher in neutral. I got it up to 4500 before backing off. It won't do over 3500 in gear though.

Cam was installed and degreed by Charlie Schmid, and if he checked it twice. There's probably very few people that have put in more Slant Six cams than Charlie.

I have the dual dutra duals running to to a Y pipe that runs through a single 2.5" pipe to a cat-back style exhaust. It should have more than enough exhaust flow. The whole system is basically brand new. That's an intriguing suggestion though.

Valve lash has been checked twice and is matched to the specs of the cam, so I really doubt it's that.

Good food for thought though, guys. Thanks!