I'm overall very happy with the performance of these speakers.
I installed the 6030cs in my 02 GMC Sierra a couple months ago to replace the stock front speakers. I replaced the 6.5 door woofers, and I installed these tweeters in the mini panels directly behind the mirrors. My head unit (and amp) is a Clarion CZ501. When I was shopping around for this speaker upgrade, my top priority was to get accurate sound reproduction. I can honestly say that the clarity and soundstage from these speakers is beautiful and accurate. The highs are crisp but not harsh. The bass output is punchy, but I wouldn't call it strong. I estimate that the low frequency volume drops off around the 70hz mark, so to get a full sound you'll need a sub. I personally was not expecting to get gobs of low end from these 6.5" speakers, so I don't consider this characteristic a negative.
If you are looking for crisp, accurate sound, then these Infinity's are definitely a good place to start. They are solidly built and fairly easy to install. I subtracted a star from 'Ease of Use' only because it wasn't immediately obvious how to get the crossover unit popped open.

These speakers are great because the cost is average and the quality is above average. It reproduces music very well and your amp will push them harder because of the impedance.

I have these mounted in a Yukon XL in the rear doors. They sound beautiful. The performance for the price is excellent. Definitely recommended these speakers.

Great speakers, very natural, a little bright, but well worth the money. Complete kit with lots of extra parts for install. Sonic is great, price is the best, price match is even better!

I have a pair of these in my yukon. They are absolutely the clearest speakers i have ever owned. I have them hooked to a four channel pioneer amp and the sound matched with subwoofers is unbelievable. Definitely buy these speakers.

These speakers are in the front of my sedan ran off 150w x2 rms amp.
Matched with 5.25" Infinities in rear, and JBL-MS-12SD4 sub getting 1000w rms. Great budget SQ setup in my opinion.
They absolutely sing, and are the best overall mid-highs I've ever gotten from any of my 4 previous setups.
I don't even want to get out of my car when a good song is on loud!
I'm even hearing musical details I usually don't notice on my ipod or home stereo.
Very sharp crisp sound.
For the $$ I doubt you could find better, clean sounding speakers!
Bass is even pretty punchy and smooth, but you will probably want a sub to compliment these.

I recently brought these speakers and got them installed. I love them alot. I had Kickers kS620 components at first and I wasn't feelin them at all. Please run them off a 4 channel amp. I'm running them off a Kicker ZX350.4 amp and it sounds so damn clear that i don't want to get out of my car. LOL! You won't be disappointed at all. I hope my reveiw helped you to choose because everyone else reviews helped me. Now stop reading and buy these Infinity Reference 6030cs!

I have had the infinity 6030cs component systems for a few months now and every one that has heard them has had only one thing to say about them they are the clearest sounding speakers they have ever heard. I would highly recommend them to any one that is looking for clarity in thar stereo system.

I would recomend these to anybody, they have great sound quality and can handle bass great, if you are building a system for ur vehicle you cant go wrong this these

I currently drive a 2009 Chevy Equinox with an Orion Cobalt CO6004 4 Channel AMP powering Infinity 6.5 Reference REF6030CS Components in front and 6.5 Reference 6032CF in the rear. I decided to buy Infinity's all around with Dynamat in the door and It sounds WAY BETTER.

Very Crisp and definitely loud. Tweeters will make your ears ring. I also like the many adapters makes it easy to mount these components anywhere. Best value out of any components. Have the older 6020s in my girlfriends car and decided to get these for mine. Replaced my old ks502 components and the sound was incredible.