If you come up with anything you'd like someone to shoot holes in, you can put the file up there and anyonw who's signed up can grab it and have a shufty at it for you. It's not as good as washing it through Dynomation (I intend to get a copy - once I have, say, $500 sitting around doing nothing else...) but it's good for guesstimates and comparison work.
The newer Runners are equal length. Each runner is capable of deliering the same volume of air. Kicking this around for awhile, I would go out on a limb and say that is a spacer did help anyone, it would be with a owner of a 99-01 with the equal length runners. Both older designs are not equal length, therefore it would not benefit as much.
As far as I know the TB opening on the intakes has stayed the same diameter. Only the runner lengths were cahnged.
I have read that the spacer on older and newer models may affect the torque curve and that's why people who swear they "feel" the increase with one. Not proven by me, just me kicking around ideas and rehashing articles that I had read.
I still am a bigger fan of getting a shop to bore your current TB straigh through.
Back to the tuning thing, which I posted about earlier (before finding this thread - duh), I just found a great link I'm sure I'll be able to digest after I print it out and read it 5 times over -