Using the 16T pulleys in place of the 25T pulleys will really help in acceleration. You will also have to change out both the main drive belt and the rear belt if you want to do this swap. (Main belt would be CT019 and rear belt would be CT011) I am not sure what the Competition drive train consites of, but its part number is CT045. I will be getting this part eventually.

The aluminum pulleys are great for better pulley strength and will last a lot longer than the plasic pulleys. (CTS16 for the 16T; CTS17 for the 17T; and CTS29 for the 25T Aluminum pulleys)

If you look for "CEN Racing", he has made quit a few posts on up-grades for the CT4S. If you look up parts numbers for the CT4S and the part numbers letter ends in "S", most cases its an up-graded part. "CEN Racing" is a real big help in all CEN products. He accually works for CEN RACING.

I replaced the 42T plastic spur gear (the green gear) with the 43T metal spur gear from the Genesis. I got tired of replacing the 42T spur gear. You may want to look into getting this gear.

I got my light kit off of E-Bay. I paid about $30, US. I will try and find the persons sight on E-Bay that I got my kit from.

If you have any other questions fell free to ask. And I will try and steer you in the right direction.

Later!