Replacing Transducer

[highbankbrew]

I currently have an Airmar B75M thru hull transducer that I have not really been happy with. The transducer is connected to a Simrad NSS12 Evo2. Almost all of my fishing is for salmon in Puget Sound (mostly the South Sound around where I live on Fox Island, but also trips further north several times a year).

I think I want to replace the B75M with a B175HW, everything I have read about that transducer sounds like it would be great for my type of fishing. The current location of the B75M does not read well while moving at much above trolling speeds. There is not really a "perfect" place to install the transducer from what I can tell due to limited access and chine/strake locations, so even though it doesn't read well at speed I'm planning to install the B175HW in the same location by enlarging the current hole.

I have a few questions about this change.

1) Is the B175HW definitely a good choice for Puget Sound salmon fishing?
2) Will the added power of the 1kW transducer (and added physical size) improve readings at speed at all?
3) Should I consider trying to move to a new location or is having the existing hole repaired, etc. not worth the effort? It's unfortunate there is no real way to test location without drilling a hole.
4) Assuming it goes in the same location, any pointers on enlarging the hole?

Thanks!