They do make more turbos for the gsr, but you may want to go with the ls. Because if you turbocharge a car, you have to start with a low compression ratio. This is because when you do forced induction, it raises the stresses in the combustion chamber and you want a motor that isn't already under higher stresses from a higher compression ratio. The vtec engine has a high compression ratio, which is not recommended when you want to turbocharge a motor. The ls has a lower compression ratio, so it is ideal for a turbo.