Hi Stevenmax50,
Is the Magnum 91 a 4 or 2 stoke. I've got 3 magnums two 75's ( 2 strokes ) one of which is in my tiger 60 and a 120 4 stroke in an 80 inch Decathalon. Like them all.
If the 91 is a 2 stroke your tiger will be a real rocket. Mine with the 75 in it is more than adequately powered and will fly quite happily on 1/2 to 2/3 throttle.
As to the retracts it would be intersting to see. I have 2 basic rules for aeromodelling. The first is don't fly other people"s models ( unless they are in trouble and ask for help ) and the second is don't build a model with retracts. They look good but are generally trouble especially with a model like this that you will love flying and use a lot. Mine has probably had over 150 flights now.
Cheers,
Tim