I am looking to replace my Permagreen Centris' engines - I have two of them that currently have the Robins-Subaru engine in them. I was able to get one of the last remaining Robins-Subarus that they had on the shelf a few years back for $380...now they want $800 for a Kawasaki with an "upgrade kit". Has anyone replaced the engines in their Centris with an engine that can just be dropped in without modifications (maybe like a Kohler or Honda, etc)? Or if anyone knows if it is a standard Kawasaki that can be purchased anywhere, just not only through PG? (I do NOT want to pay that price if I can get away with it). And if the Kawasaki is a standard stock engine, what does this upgrade kit consist of and is it really necessary to have? Any information that anyone has would be very helpful. Thanks!!