Max, whatever would you like me to rebut? The physical limitations in that area above the M112 and below the hood dictates whatever is choosen to to be squeezed in there. There are more qualified minds out there than mine, that can factor every calculation into each variable, but what the goal to achieve is as near as we can, is the most optimal vs the most practical. Yes, there is a fine line easily crossed, where an audience is turned off (been there, done that). I like the way you explain to (at least) this simple mind, what you considered for your install. Not many would use the engine IAT, opting for an IR gun (subjective, as its application is suspect for the consistancy of accuracy), or mounting some other device wherever they want, for testing/proving their install. The engineers at MB (or whomever was hired to put that powerplant into the car) chose the location for that particular sensor, and if it was ok to them then why move the location in an attempt to modify the intake? Obviousely we hope they spent quality time on every aspect of that design given the brand and price of those engines when they were MB's, right? Anyway, I'm not rebut-ing your install, nor challenging your calculations, I like what you did, it qualifies for an actual CAI, and it looks great!

My reason for asking about the metal vs plastic in the intake path was because of the thermal activity inside the engine compartment during idle, at rest. Having the cooler intake air BTU's migrate into those metal components (cold to hot) is annoying but thats physics/thermal dynamics! Yes, most of the time its moving down the road and that period of time there is only some minimal thermal influence, its just I was trying to understand your results better (125 F at idle IAT). Also, the recovery may be quicker (your note that it seemd to recover sooner) with your CAI as installed (but then we do have all that thermal energy in that metal don't we?). I know it would be time involved to check recovery with both systems (OEM/CAI), but if you ever get bored someday, it would be nice to know. Personally, if I install one, I would be looking for something less 'thermal' retentive (as opposed to **** retentive), unless I just wanted the look and didn't care about the resuls of that questionable thermal influence. Given what I just mentioned, it (the non-metal tubing) would have to follow the plan of 'larger-to-smaller' from those bulkhead supports to the throttlebody (like yours does). I do not want any (intake) air compression after those rather small openings next to the radiator, all the way to the MAF opening. After that MAF, its back on the MB engineers (here's hoping they did ALL their calcualtions, arent we?). Oh, did you measure the cross-sectional openings (at those radiator bulkhead openings) when you had everything apart? I would guess they are @ 105%(+/-) total volume above the MAF opening (just a WAG).

No rebutal, just idle banter between XF owners?

Edit added the "(at those radiator bulkhead openings)" 2nd para., 2nd to last sentence.