Having the original manifold leak at #6 after 100,000 miles. I opted to replace with another factory unit. Genos has a fantastic price on the replacement units and sells the gaskets to boot. The entire job wasn't hard at all. I started each top bolt with the gasket hanging, aligned the bottoms and torqued everything back down. So far, so good. The most difficult part was moving the coolant pipe away from the bottom stub at number 6. I just cannot see spending 400 plus on an aftermarket unit that may or may not last as long as the stock one. Having run an aftermarket unit on my son's '03, we really coudn't tell the difference in performance, cooler EGTs, etc.