I would recommend the Technigas as a direct bolt on. You should get about 42-44mph with a 22 rear gear. Jet to about a 58-59 and you should be good.
The Imperial Blitz pipe by inherent design is only good for about 38-39mph, but good on the torque.
My recommendation, however is the Tecno Estoril. If someone can help you reweld the flange angle to fit. The exhaust was made for the A35. A55s have a different exhaust flange angle. This pipe has the widest power band I know of, and still gets out to 43-45mph.
I have a '08 SMR with a modified bullet and some minor porting on my A55 50cc. I run 53 on the flats all day long. I whoop on kits all day long. AND i don't have to premix!!