Finding anyone to touch anything other than a old 300xs is going to be difficult. Mercury won their lawsuit against some companies that were modifying PCM's and it cost them a pretty penny. Last time I asked about my 250xs they all acted like I was asking for cocaine.
It pisses me off that some models can be modded and almost everything else cannot. Also that Yamaha and every vehicle on the road can be without penalty (unless it is a diesel). Because according to Mercury we don't own it.
But it is what it is until someone is willing to fight Mercury with way more money than I.