Guys
I have a O.S. 91Fx two stroke engine and a Bission Pitts Muffler. I consider myself a intermediate RC pilot.
Looking for opinions and suggestions on which model to put this engine into. At this time I have been thinking of building one of the two kits from Goldberg Products, The Ultimate 10-300 or Extra 300.

That's an easy one. All real planes have 2 wings!!! Ultimate all the way!!

Ken

These are both great airplanes. I am on my second Extra 300 over the last 10-12 years, both with a Webra 120 in them. And I have the Ultimate that is about 10 years old, with a 108 ASP. Your 91 will fly either one "nicely" but not in a breath-taking manner. Pick the one you think is the neatest and go for it!

Clair

They are both great planes. I have had two Ultimates and am still flying the Extra after about 8 years. All in all the Extra is the better flying plane and field assembly time is less. But those two wingers are great too. It really comes down to your personal preference.

Thanks guy's for the suggestions!

DVI:

I have had both planes, They are not equal.

Extra 300 is a mid wing that loves to fly, it has the same stall speed as a LT-40, 17 MPH, according to RCM articule 3 or 4 yrs ago! it´s only big faulty is the landing gear that You can replace for and aluminun one, also You should change the wing sheeting for 1/8 and also build a hatch under the tank.

Ultimate is a different animal, does better aerobatics in general, loves knife edges you name it..., thougher to land too, it has the same building tips as the extra.

If You are an intermedia flyer, the joy of flying the extra is max, if you wish to challenge yourself to the next level the Ulty is the ticket.

The set up on the extra is OS 120 4-s don´t recall the last prop used, on the Ultimate is OS 90 2-s 15x6 pro-zinger, perry pump.

Both set ups works fine although I have seen ultimates fly with 90 2-s 13x8 and 14x6, I stll like the 15x6 better.

hope this helps!

Would the saito 1.20 be a good matchup for the ultimate? what would the vertical be like here? Between the 1.20 and the 1.50, US$40 price difference but I do not want to overpower the airframe.

It is around 8.5 lbs. the 150 is a lot, although it depends on how high your flying flield is!!
truth is the lighter you keep it the better, so check weight between engines that shall give You a better clue.

thanks mancha, the 1.50 is 30 oz while the 1.20 is 28 oz. Weight on the 1.50 is not really an issue, but I will likely be going with a 1.20.

Elevation here in PA is around 400-600 feet.