if you have a 92 camry, i think Brospeed header fit? not positive.
but if you have a 5SFE engine, rippmods header is the way to go. i love mine.
difference? well, by themselves not much. but w/ proper intake, and proper catback, it's awesome. that's why most people suggest first mods as "intake, header, and exhaust." not just one. think of it as an entire package. it all makes the car breathe better.
i had my intake first (short-ram) then catback. good results. then added rippmods header, and even better results
and finally short-ram to true CAI, and the best results so far!
I haven't dyno'd yet, but i agree w/ userlain. probably around 10whp total w/ all the mods together. but i think it's more w/ torque...i felt more torque gain than hp. (torque in lower end, hp above 3500 rpm.)