all depends on your engine. if ya engine starts making power and torque at 3000 then get a 3000 converter. if your engine starts making power at 4000 get a 4000 convertor. if your engine starts making power at 2500 get a 2500. no use making it too small if your engine starts working at a higher rpm as it will bog down before it gets going, no use going too high else youll just break out in wheel spin and loose effect.
tall ya a story, i had this XA falcon come in for a wheel alignment one day, had this lumpy cam in it and the owner reckoned it ran 10's down the strip. when i drove it prior to wheel alignment, not thrashing it, it seemed a gutless pig and here i am thinking hes a tosser wanking off.
After alignment i decided to wind it out and see what its made of. down a long quiet back street where i go to test drive things i decided to give it a boot full. started off like an old granny diesel gemini and im here thinking what a load of crap. then when the revs hit 4000, all of a sudden it hits its power band and im left with dirty undies.
That was 10 years ago and i still havent forgotten, it scared the absolute crap out of me, it lurched forward with the front left lifting up and gave me a hell of a fright it went that damn quick.