Imo i think it depends. If you are building a purpose build race car and that is the only thing your gonna do with it then yea a custom single use converter is probably necessary. But (and yea i know were on the racers forum) but the way we use our cars, and by we i mean guys like you, me, j par, jaba, sam, etc the guys that actually drive their cars ( or want to lol) then a multi purpose converter would be nice. I know when i asked on here about a stall multiple people told me 3500 when i called the company (brand converter i purchased) they told me do not get a stall higher than my cruising speed or lower than my cam power start. My cam (power range) is from 1500-5000 and my cruising rpm is around 2800 so i chose a stall that was 1600-2200 now granted that 3500 stall that everyone recommended may give me a better quartermile time but thats not my goal.