Took these off yesterday. This morning about 1100 the car was running several degrees cooler...like 201 instead of 207. Nice improvement. But the real improvement was in performance and sound it sounded meaner.
I made some honeycomb fog light inserts and have been running those since spring. Temps might be a touch lower, I haven't noticed any sound difference. Although, I have removed the sound tube and changed the exhaust baffles to 3/4" about the same time, so who knows...