Hi Geo, thanks for the warning. I am aware of this situation. Based on the only review, the shift knob will get about 5 degrees hotter than stock 987 knob. With the AC blasting, it shouldn't take more than a minute for it to cool down. I do not drive the Boxster often and having a pair of driving gloves on standby should help alleviate this problem.
I think for most owners with a black interior and the top down during hot days, we've all experience the hot interior cabin before. I've been burn more than once or twice by that dashboard

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I installed the shift knob the other day when it was near 100 degrees and after 2 hours I did experience the warm/hot touch to it; top up. I'm waiting for the new leather shift boot to arrive to finish the job.