Can my crunch 1500.1 be to much for my two Alpine type r's?

I recently got my new system it consist of 2 4ohm Alpine Type R's in a custom sealed box(all i can fit in my tiny trunk(Honda Prelude)), a crunch power zone 1500.1 which is one ohm stable. I hooked it up but upon trying to tune it in no matter how i tune the speakers seem to distort when i turn it up.I checked all wiring from amp to box to the speaker both are the same. Any idea what could be causing this? All out of idea these things should pound hard but they are not i have friends with two kickers and a tiny amp blowing mine outta the water.I even messed with my head unit its a kenwood excelon so it pretty high end. Help is greatly appreciated.Thanks