A good 3 angle is fine for most people, 5 angles if you want that extra last bit. Whether that extra bit is worth the extra money is up to the individual...

I dont know a thing about the Reno or why it gets horrible gas mileage but it probably has a lot to do with cylinder head design/efficiency...You may not see incredible gains on a stock Reno but it could help. Sounds like that head just needs a really good port job and maybe some bigger valves...