The rear speakers are spec'd at 3 ohms. Only bad thing with just bypassing the stock amp is the impedance doubles being drawn for the rear channel. That can cause a quick death of an aftermarket HU. The amp and rear speakers worked fine in mine after changing the HU, I changed to a aftermarket amp for the door speakers for tailgating and just had to run a remote trigger wire back to it. I also cut my doors out a bit and installed a set of 3 way 6x9's.
My HU specs are 4-8 ohms, So I did a bit if research to see how compatible that is for 3ohms. Biker80, let me know if you disagree, I'm just relying on what the internet tells me (So you know it's all correct) A few sites I've visited have pretty similar answers. But I'm still considering getting a set of 4-8ohm speakers to be safe.
Taken From Another Site: http://www.sonicownersforum.com/forum/i ... m-amp.html \/ \/ \/ \/ \/ \/
This may make you feel a bit better.
2 ohms, 4 ohms, 8 ohms is a nominal measurement. an 8 ohm speaker may dip as low as 4 ohms at certain frequencies and may go up to 15+ ohms at other frequencies.
That so called '8 ohm speaker' can look like anything from 4 to 15+ ohms to the amplifier especially if a passive crossover is used.
Point is, that 3 ohm speaker will almost never look like 3 ohms to the amplifier so its really no different then a 2 ohm or 4 ohm nominal speaker. Its just a general guide and as sonic007 said it will be fine. If the amplifier was running borderline hot to begin with it may cause a problem but that shouldn't be the case.
Overall a 2 ohm speaker looks like a lower impedance then a 4 ohm and that 3 ohm will appear slightly lower then a 4 ohm but nothing will care.
This may give you an idea of what I'm talking about.
Full disclosure: I have no idea what that graph says [\b]