RE: Venus II
Don't get me wrong the 90 will fly them you'll just be wanting more power, to hard to pull a good loop without good power.
The best thing would be to sell the 90 and get the Webra 120 which is an awesome engine once set then just fly, we have 2 of these in our club that run perfect and have the power needed, one is pumped the other isn't and they run the same.
[link]http://www.horizonhobby.com/Products/Default.aspx?ProdID=WEBE919[/link]
Steve