I have a MY99 impreza 2.5RS and i was wondering if a EJ20 or EJ22 block will fit on my car, or will i have to do more than just change the block? thanks for your help.

I'd prefer to do the EJ20, simply because I think the ej20 block will be easier for me to get. so please let me know what is needed to be done in order for this to work.

don't take this the wrong way, but this is adressed in about 5 threads in this particular forum, read about the conversions, you will get your answer.