Could someone link me to an middle line set of speakers for a 99 eclipse gs, not stock speakers, I need some really nice ones that are 300 watt.

why 300 watts, what are you gonna run them with?

And which ones, back or front?

You don't need 300watt speakers unless you are going to get a good aftermarket amp. The headunit will only do 25rms to them.

Front:
Pioneer
Infinity

Rear:
Pioneer
Infinity
eclipse
diamond
Blaupunkt

just swap for pioneer throughout for stock speakers and get a pioneer premier head unit. then you'll be thumpin harder than any other "upgraded" stock system like the "infinity system", or the "bose system" i know bobthecow hates when people mention that company its fun to read about how much he hates "bose" LOL it probably just as funny when people mention crutchfield and i reply to that.......