Greetings:
The 5th one looks like the one Taz sold me. The brand name appears to be "Hot Surface, Do Not Touch".

Bolted to Flash III - 78cc Nicasil and OKO 30mm carb for now - it
oozes with low-end torque. Installed a bone-stock Kymco clutch, complete with stock springs so it engages just off idle. Danged if this thing doesn't just
Motor away as low as 2500 RPM, something the PG Long would absolutely refuse to do.
I need to swap to lighter rollers to see for sure, but I have a feeling the pipe closes down the party at about 8K RPM.
Up to that engine speed, power's
great!