i pulled this up from another thread and added the JP-3 & JP-4 to it. I've not messed around to much with pipes so I can't confirm this is 100% accurate but no one seemed to dispute it in the older thread so it should be good info...hope it helps
for pipe decoding:
Ofna, Novarossi, RBConcepts:
063=bottom end pipe
053=mid-range with good fuel mileage
086=good top and bottom end, not the best fuel mileage
OS:
2050=mid-range, the fuel mileage master
Picco:
069=mid-bottom, ok mileage
Jammin:
JP-1=identical design to Picco 069
JP-2=mid-top end pipe, ok mileage. modelled after another picco pipe but I'm not sure which one.
JP-4=mid to top end without sacrificing much low end punch.
I believe JP-3 is similar to the JP-4 in that it is classed as an all around pipe but the JP-3 isnt race legal.