195-205 is fine anything above 230 is bad mine in stand still traffic at rush hour for about 15 mins of idleing never gets above 205. i forgot it a few times and it hit 220 but the fan brought it down to 205 in just over a min. i forgot i traded my buddy my 2 16" fans for his one big one. so hes got it. go to the junk yard and pull one for 30 bucks.
yes it makes life sooooo much easyer for belts i replaced my alt and tenisoner after doing E-fans and holy crap it was easy!!!
as for your mileage...frist tank will prob suck bc ull be into it alot because of the new found power
