PIAA 540 vs. 510 Ion Crystal Fog...POLL

I am trying to select between the PIAA 510 and 540 Ion Crystal Fog light based on the most up to date information and personal experiences out there.

My bumper will fit either a 510 with the PIAA grill or the 540 with out the grill. My understanding is both versions use the same bulb. Since the 540 lamp is larger does it perform better or worse than the 510 smaller sized lamp...?

Which lamp would perform the best?

Where is the best place to purchase PIAA these days?

 

I dont have experience with the 540's..he'll, I don't even know what they look like. I do however have the 510's and for me they are plenty bright with a great pattern that fills in perfectly with the regular headlight pattern. I have them mounted in my allpro bumper without the plastic grill thingy. Had them for about two years now without issue..except for replacing a burnt out bulb. I also have them spliced into the stock fog light harness.

Edit: I purchased my lights from AllPro Offroad

 

The 540's are 6"

 

Anyone else?