My first plane was a Hobbistar 60 with a .65LA. I thought it was a great plane.

Do what you'd like, but the .65 is plently of power. I snapped the middle of the wing three times (had to apply new epoxy each time) and didn't realize it until I landed and only the rubber-bands were holding her together.

Not sure abou the tuned pipe for a .65, but with or without, the plane is fun for a first plane.