Used WRX STI and then mods or used STI RA?

Hi, I’m considering a gently used Wrx sti or used
RA.  If want to add some basic mods to STI, such
as exhaust/tune/perhaps intake.  Since RA already
has those modification, plus forged pistons, would
it make more sense to purchase a lightly used RA
to keep the warranty. Plus I thought it’s probably
safer to purchase RA since all those cars were
probably beat on from the break in period, and
since the engine is tougher in RA, it may have less
wear, being purchased used.  Any thoughts would
be appreciated.  Thanks