M20B25 Valve seat recut

[zaq123]

Can anyone please tell me what angles should I have the shop to recut my EX and IN valve seats in the prep for my new valves? Should I back cut new valves for the better flow as well? three angle cut? four angle cut?
Thank you in advance

[jeffnhiscars]

I do a 3 angle seat and a back cut

[zaq123]

I do a 3 angle seat and a back cut

What angles do you guys recommend? IN EX? 15 46 75 for IN? EX??
Thank you