I looked into Nelson Rudisill's (NKR) repro cowl plenums a couple of years ago. Back then, the major differences in his air cleaner as compared to an original were in the air cleaner lid and in the material used in the duct. In my opinion, a 1st gen Camaro Z/28 "expert" can easily tell the difference between one of his repros and an original. But, probably 95% of Camaro owners can't tell the difference between an original and a repro. I happen to be lucky enough to own an original 67 Z with an original cowl plenum air cleaner, but that's only because I got into this stuff way back when the stuff was affordable. If I was just getting in to this stuff today, I'd have no problem buying the repro cowl plenum air cleaner for a nice car. After all, even if you have the money, there's just not a lot of original units to buy anyway!! Just my two cents.
