Some may disagree, but take it from a man who tried to fly a glass Dirty Birdy with a side exhaust X60 - you WILL want more power unless your UFO is MUCH LIGHTER than my DB was. A Super Tigre S-61 or Como 61 will drop right into the same mount as the X60 and make a LOT more power. Photo shows good friend Steve G. posing with my DB after the S-61 was installed.

Another reason I mention this is that the X60 requires an adapter plate and a header to fit which is not interchangable with any other ST 61. The S-61/Como 61 use a simple bolt-thru header. YMMV.