Because dbw cars factory tune is much leaner. Valves run hotter.

My understanding is if you have Flashpro, most tuners tune based on primarily (but certainly not exclusively) on afr. Meaning asasideeffect of tune, any factory tendency to run lean will likely be tuned out if you get FP and a tune. Meaning you'll likely eliminate the tendency for your valves to tighten sooner than other S versions.

Be aware though if your valves were already partially burnt due to valves getting too tight, subsequently correcting afr with a tune may only slow down the continued deterioration of your valves seats. They will likely still tighten sooner than, say, '04 or '05 ap2.

 

Yes, i know. This should be a hint for S2000 owners in the US or elswhere to check valves more often if you visit a racetrack sometimes.

 

Yeah, but I think they covered that with the 'severe duty' service interval recommendations...

 

It has been a few years but I recall seeing a post that there was something like a 28 second limit of WOT in any one gear. (Being in aviation, I tend to gravitate to limitations) I can only think of a few places that could actually happen and the autobahn is one of them.

 

I'm not sure I completely understand why higher temps cause the valve gaps to change quicker.

 

Gaps tightening is caused by valve recession. The valve head pressing further into valve seat, due to erosion and compression of the valve seat. This is exacerbated by extreme heat into the metal.

Exhaust valves get heated by hot exhaust flowing through, while intakes get cooled by fresh charge. So exhaust will be the ones to receed more than intake.