I say port your stockers unless you just like spending money. The v-force is good but you will noy get the gains you expect for $220 unless your motor is ported. If your planning on porting in the near future go for it.
There is torque specs for allmost everything but at the dealer ship when assembling a new quad I just set my impact on 2 and run em tight. Never had a problem.
It's normal to have a little oil in your header pipes right around the flange but you don't want oil coming out at your silencers. You might have just a little to much oil mixed with you gas. Some oils call for 32.1 and some call for 50.1
Anytime you buy something one part at a time it cost you, a package deal is always best even if you don't use the other gaskets it's good to have the extra intake gaskets cause it's easy to rip one while taking off your reed cages.
Run whatever you like but I run the 15-41 and it does the best with a 20 inch tire. You might like the low gear but I don't like shifting gears that much. I also know guys running 15-41 with 22's and it does good also.
I have rode the 450 several times and it's an awsome bike, by far the best stock quad made. But it has it's limits and does not give you the rush a banshee does. I have considered getting one for a backup ride but definately not gonna trade the shee for one.
We read coils and stators and pickups all the time at the stealership and use yamaha service manuals and if it don't read to specs it is bad. If the spec says .2-.8 and you read something like .9 it will usually work cause the meter could be off that much, but if it's way off it's bad or the wire is bad going to it. Make sure your fingers don't come into contact with the leads or it will read your resistance.
You could also have an airleak around yyour intake gaskets or balance pipe which is leaning it out. You need to find the problem before you ride anymore incase your lean.
I put mine on with stock pipes and felt better throttle response. With pipes it feels like it revs higher but looses power before the powerband. It also sounds different with it. So I run without mine.
That's a salesman for you. He probably beat one banshee that was on it's last leg and the rider was not that good. I used to go to the sand dunes in albany georgia and race guys with 400ex and craptors and get beat cause I was running my paddles and they would only line up on hard packed clay with me. I would ask them to run in soft sand and they wouldn't. So I went back with my holeshots and waxed that ass.
You really don't need the splash gaurds cause I run without them with no problem. As far as the dealership I work in the shop at one and I would take that back and make them fix their mistakes. It sounds like some rookie worked on your bike. My boss the service manager does all the high performance work and if something is not done right he will fix it to keep the customer happy.