With the final 300 number in mind. All the motor needs is forged pistons and rods to handle this.. Lets say $700 on that. Then a piece together turbo kit can be made to reach the 300whp mark for around $1,000, Finally a megasquirt setup for $400-$500.. So we are talking $2,500 total... He might get $2,000 for his GS. Which he will have to sell to purchase a GST for $4,000 (a decent one) Then he will need to sink $1,000 plus to reach 300 on the GST.....So all together if he stays with the 420a it will only cost him $2,500. Compared to $3,000 or more, and the hassle of selling his old whip and finding a new one!