Broken Denso IT-22. What plug next?

[orange04]

I was checking afr ratio on my Cobra this weekend and after a WOT pass my car began to idle rough, 11.7-12.0 across on RWTD tune. KB 17 psi. I pulled #2 plug and notice the plug was broken and dropped over the electrode. I pulled all plugs and all the rest were ok. I put my NGK TR6s back in and the vehicle runs good except for idle, there is a slight popping in the exhaust that I dont like. The Denso cured the idling concern, What plugs are comparable to Denso as far as idle quality. I want to stay away from Brisk per James. Any ideas, Ive searched and found some guys are ok with IT-24s. Thanks in advance guys.