Is the I6 in the GS300 the same as the I6 in the IS300? Will the same performance mods for the IS300 (like turbos) work in the GS300 too?

 

i doubt, coz' the ecu are not the same, so tuning might be different. in terms of brackets and spacing the two cars might be different too

 

IS300 Headers will fit.

 

Most of the usual stuff like intakes & headers, heat shields, etc will work... Y pipes are different, The GS needs a longer Y pipe.. .but the header is exact... the Supercharger kits LMW sells also will bolt right up even easier than on an IS due to more space available....

cant think of many other usual power mods folks try that would work ok....