modifying stock TC
 

I have been looking itno beefing upthe trans and I have been informaed that the TC is the main prt to go for..after a few calls no onelocal to me in UK can get hold of any of the good brands Banks etc. But i have been offered a service of modifying my current TC they say they can weld the fins and a few other things (I don;t understand any of it, i'm not an auto guy, yet) they say they should be able to improve its holding power between 15% and 50%.
My question is what is the stock TC's rating? and is this sort of modification work, usually relaible, bearing in mind i'm not gonna go over 300BHP or abusing the truck much. I'm hoping its a worthy option as i can get this done for a 1/4 of the price of a banks billet converter and i wont be making enough ponies to use abit of kit like that to its ful potential anyway.

Thanks, Bill