I've somehow ended up with two ODB-3's. So I modded one with a few mods from Brian Wamplers pdf's. I didn't bother with the 4148's, but the other 3 changes improve it a lot :-
[color=#000000][font=Verdana, Arial, Helvetica, sans-serif][size=3]easy mod to make it much nicer:[/size][/font][/color]
[color=#000000][font=Verdana, Arial, Helvetica, sans-serif][size=3]c10: 1uf[/size][/font][/color]
[color=#000000][font=Verdana, Arial, Helvetica, sans-serif][size=3]r31: 1k[/size][/font][/color]
[color=#000000][font=Verdana, Arial, Helvetica, sans-serif][size=3]c8: .001uf[/size][/font][/color]
[color=#000000][font=Verdana, Arial, Helvetica, sans-serif][size=3]for more smoother compressed tone, change d2 and d3 to 1n4148's[/size][/font][/color]
Sounds quite good now (much less fizzy) and has even made onto my board a few times recently.