positive/negative wires?

What are you refering to, positive and negative power leads? Speaker leads? Need a little more info before we can heldouble-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer

If the leads were wrong then the symptom would be lack of bass response due to out-of-phase signals to the two stereo speakers.  Breaking up at higher volumes is usually attributed to either a too-low crossover setting for the speakers, or clipping of the amp due to improper gain setting.

A trick I learned a while back:9 times out of 10 (all the time in my case)If you flip the stock speaker over and have it next to the new speaker, line the terminals up together. If you see the wire from the car that connects to the left most lead on the stock speaker, it should connect to the same left side of the new speaker. And the right should connect to the right.Out of the hundreds of speaker upgrades I have done, this has never failed.Of course, most new car have clips that companies like Metra Electronics have a molex mate, so you don't have to cut stock wires.This works I think because speakers are all built the same way (generally speaking, of course), regardless of factory or aftermarket design.Hope this helps.DXAV