I had 310hp with boost spike, unopened motor, gtr inj, ems and 6boobs mani, lasted 5yrs before i pulled it out for teh restoration. The 25 conversion is up to you really if you feel like you wana go that way. My old turbo setup is going onto a 25 in a 31. I was going to go down a stroked 25 route but changed my mind for the 26/30 which would have cost the same.
The 20 is a great base to play with they just love to rev