Here are two easy upgrades I just installed using old parts a fellow motorized bicycle and Moped enthusiast gave me. The first is a Cam-style chain adjuster that simply goes between you drop out and your axle nut. You simply loosen the two axle nuts, twist the cam until your chain tightens to your liking, adjust the opposite side so your wheel is straight, and re-tighten the nuts. Without the adjusters my chain would loosen up no matter how much I tightened the axle nuts due to the engine torque in low gear. Now, there is no way for the axle to slide forward so the chain stays perfectly adjusted eliminating chain slap and excess wear caused by misalignment from the loose chain. The second upgrade is a Biturbo expansion chamber that comes with a 25 or 26 mm ID header pipe which will allow my reed valve engine to breathe a little deeper. The expansion chamber will accomodate several custom silencers. You will note from the photos I have not fabricated the silencer and/or stinger. I hacked and welded the header onto a steel manifold I made from 1 1/2" channel. I like these pipes because the steel is thick and doesn't perforate when I have my Lincoln welder on 105 amps using soft 7016 rods. I installed the pipe in a swept up angle to make the bike look like it's going faster. Attached is a photo of the old exhaust for comparison. Both upgrades took about 4 hours to install. I will report back on how the pipe works (and sounds).