These Suzukis are heavily restricted by the exhaust. Early machines have a one-piece exhaust which must be replaced, and although they also have differences in the CDI, air box and cylinder barrel, the major restriction is the exhaust.
Later machines have two-piece exhausts - the front pipe and box being bolted together and the bolts welded over. These engine units, CDI’s etc. are identical to the full power motors and the only restriction is the exhaust. However, the restricter in the box can be removed by grinding off the welded bolts that secure the front pipe to the main box. After splitting the box like this the restricter can be found in the entrance to the main box. The front pipe is much shorter on the full power exhaust and no replacements for this have been made available yet. The best way to obtain good power is by changing this exhaust as well.
Our favourite exhaust is the Giannelli Procee. See the dyno graphs for differences - please note that these are real speeds and power is at the rear wheel.

Dynojet graph comparing the Suzuki Katana 50 LC
with and without a Giannelli Procee Exhaust

Because of the very low gearing used as standard on these machines the higher revving LeoVinci handmade exhausts are not recommended unless a gear kit is used. The LeoVinci revs out to 12,000rpm on standard gearing and peak power is at 9,500rpm. This over-revving on standard gearing gives long term reliability problems with the crank and big end bearings, especially if fully synthetic two-stroke oils are not being used.