if u wanna go ahead and do your own research on either the 4g63 or the chyrsler 420a here are some links...

2gnt.com (everything 420a performance, very informative if u end up getting an rs/gs eclipse or eagle talon esi)

dsmtuners.com and dsmtalk.com (probably the best info you can get anywhere for all things 4g63...7 or 6 bolt)