I've dealt with Richard before too, cannot speak highly enough about him for service and ANSWERING THE PHONE! He called me back right away one time regarding a question when he wasn't there.
I have a fuel boss, the 2 filter w/ water-fuel seperator thing, the stock fuel filter bypass thing. The kits are very very complete, I'm afraid lots of other places don't have nearly the completness of GDP's kits.
Looking at the stuff you get (pump, hoses, brass adapters, etc. etc. )it's clearly high quality stuff, and I like the modularity (seperate pump, filter) and it's affordable to even buy a spare pump if you're so inclined (I'm not)
The fuel boss mechanical pump you can set as a complete seperate system, so you don't replace the OEM fuel pump, you have a seperate fuel intake 'straw' lines to the new pump and filter, regulator valve that send excess back to tank etc. There is a Hobb's pressure switch that only turns on your electric pump between keying your ignition switch and starting, and if your new 'drawstraw' is higher than the level of fuel in tank (so pressure drops). You can't really replace the existing drawstraw in the tank with a bigger one that is in the optiminum place (but you can get it close) because the existing fuel pickup is 'molded in' the bottom of tank. Also the mech. fuel pump is cool because when your RPM's are up, so is your fuel pressure unlike a electric system. The mech. pump can pump way more than you need, and you can replace the spring in the regulator so you can increase pressure to the CP3 up to like 90 or 100 lbs. I believe if you want.