MOPED ARMY

Im not entirely sure that you have to rejet with an exhaust. But, everyone seems to recommend it. I think it might be because expansion exhausts push unburnt mixture which would otherwise exit out the exhaust back into the motor. So the extra fuel gets pushed back in resulting in more power, and making better use of the expansion chamber. Im no expert but as a quick answer Id probably go up 2 sizes.

As for air box mods, just figure out where the restriction is, and de-restrict it. You could even run no air box, but I dont recommend running no air filter. If you de-restrict your air box, then you pretty much have to upjet or you will be running leaner, you have to be careful not to run too lean or your motor may not receive proper lubrication. Id say another 2 sizes for a simple de-restriction.

So for a quick answer from a person without much experience in this, Id say go up 4 sizes if you do both.

I dont know much about Tomos, so I dont know what size jet they come with stock. But if you take the jet out I think it should be labeled. Someone here probably knows though.

Generally carbs come with an air box as standard.

No putting more oil in is probably not a good idea.

The jet that comes in it is a #53. With the biturbo I ran a #56 jet and that was perfect for me. Should be in the ballpark. I just ran it with the stock filter. Your speedo says 32mph. That is not accurate. But your speedo is going to say low fortys with the biturbo. I'm not saying you'll be going that fast. But the speedometer will be reading that high. Mine was reading about 45mph when I had mine.