I have run BOTH Super tigre and OS for years. the two supertigres 45 's have run FLAWLESSLY & I mean FLAWLESSLY for a very long time.supertigre engines are not overweight by any means . if you think that, I wonder what you'd say about HB , which are. recommending a pipe , unless you need lots of power is bad advice & useless unless you know how to set it up. OS has a great ,if sometimes inflated, reputation. parts are easy to find, even for older models. they will run on FAI fuel ok. I have also run Thundertiger pro & HB with great results. you may want to check out MECOA engines. site.