Proptop- I'll put down my drink and give this a shot... The YS-45 is a $170 engine- generous gift!
The YS-45 can be run on a Macs 7.5 or 8.5CC pipe, my understanding is that the 7.5 is better for higher rpm's
and the 8.5 is for bigger load (Pattern prop maybe-)
The Webra/UT combo actually sounds like it'd be REAL strong-
I always ran 20/20 Powermaster, a 10x7 even 10x8 (9x9 would be fun..), and OS-8 plug. I bet you could hit 17K or more with a 10x7 and a matched pipe -
Also make sure your tank is adequate as the YS pump style can ruin many a tank- hayes tanks are good...
Other than a Jett-50, the YS-45 on a 7.5CC pipe would be my top choice on a go fast bird like a Patriot, Cobra etc.
I am sure someone else will give better advice or even correct mine here soon- Bob27? You around?
Cheers!