I think the best Intake manifold available for a 340 or 360 is the Edebrock Performer RPM. The ports on this manifold are too big for 318 heads though, so the obvious choice for a 318 would be an Edebrock Performer. Well, not so fast... That's what I thought, but after talking to Ryan at Shady Dell Speed Shop I think there's a better choice. He recommended the Weiand Action Plus manifold as being "quite a bit better" than the Performer. I talked it over with my machinist and he agreed, so I went ahead and purchased one. Like the Performer, it has intake runners that are sized for the 318 intake ports. However, it is a good 1" taller than the Performer and has smoother curves in the intake runners like the Performer RPM. In fact from looking at it I'd almost call it a Performer RPM for the 318. Also, the Performer has provisions cast in for a factory style choke. If you're running one it's necessary, but if not it's just another cranny for gunk to accumulate.