For the most part peak is a sales pitch for cheap subs. Rms is what is importend and you want to match the rms of the amp to the sub/s. also the ohms is a big part a cheap sub may say 2000 watts peak but that may be at 1 or even 1/2 ohms if your amp is 2 ohm stable then it wont match the sub so look to match the rms and ohms of your speaker to your amp/radio for a good sound without damage to your system.