What he said!
Been there and done that, twice. First set lasted 15,000 kms or so, second set was 1,000 or 1,500. Forget them! HKS Japan even say to run the standard manifolds (Ask Elrodeo666 who had his HKS 2.8 built by HKS Japan.... That in itself says something!!!!)
ID 2000's. Great choice. Even though they flow enough to be fire hydrants, they idle and drive better than atleast the Sard 800's ever could dream of!