Upgrading tweeters JBL system

So I have already upgraded my car with Alpine 6.5s in the doors and an Alpine 500w amp powering a 10inch alpine type R. I like my system, even though it's just running off the stock head unit. The thing is that It's hard to hear the treble over the bass. I just bought a pair of JBL tweeters model p26t that I'm getting installed at Best Buy over the weekend. When I took them in to book an appointment the guy said they would work fine and I wouldn't need to use the crossovers they came with which are pretty beefy, maybe 2"x2" and 0.5" deep.

So is he right? I've done my research and it appears that the stock tweeters up front are 6ohms but the ones I bought are 4ohms. I'm worried that without the crossovers the system will sound distorted and since I'm gonna have to cut up the brackets I won't be able to swap the factory ones back to compare.

Should I insist that he install the crossovers as well or would a resistor like the ones on the normal tweeters work just fine? I have a suspicion that he is telling me I'll be fine without installing the crossovers out of laziness since installing the crossovers would require removing the door panel.

The reason why I am going with Best Buy instead of another shop is because I work there so I get a discount, so another shop is out of my price range.

Anyone whose upgraded their system feel free to chime in. I also have an extra pair of alpine crossovers I never used that came with an old set of alpine components. Maybe I could get him to install those, they look like it would be easier since they are long and thin.

 

So I got them installed for $10! Don't really notice much of a difference, they sound different but not better. Since the tweeter signal comes directly from the amp, there's no way use the crossovers and run them off of the front door woofers. I think I will probably return these and get 6 ohm speakers installed. Or save up and just buy a real headunit (long way away)

Who knows of any 6 ohm tweeters that would fit into the stock openings?