Hi Kevin,
Yes, you should run your machine at full 3500 PSI, and you can either use 1503, 2503 or 4003 spray tips. (the 03 indicates the tip is rated at 3 GPM. ie. our 9 GPM machines use 2 - 1545 or 2545 tips per Hydro Tek ANT 3 spinner).
15 degree on very sturdy and well cured concrete, 25...