I have a 2010 base mdx...Ive been searching the net and counted atleast 20 people with the exact same issue. This is not suspension related. This is absolutly an intake backfire or an explosion withen the cat(s) only happens going slightly up hill full throttle 1st to 2nd shift. During the shift is when the loud noise happens. Here is the kicker.. im a 15 year Honda mechanic. I know my way around Hondas. No Honda ive driven does this.. i believe its a glitch in the Acura pcm software. Unfortunately i do not have access to Acura resources.. no access to inACURA. Nothing. No friends at Acura.. most of the reports i read were mdx's under 5k miles. Everyone including myself runs 92-93 octane. (I use top teir 93) but fuel is not the cause. When i bought my X last month it had a full tank of 87... yea thanks dealer. But the backfire happened with the 87 and 2 other times on 93. Nothings wrong with my X. I just had it fully apart for the 105k. (T-belt-Valve adj.. plugs. Its sound. Has 130k miles. I know im not the only one... anyone take theirs in to Acura with results? Also being that im a Certified Master tech. I will most likely be chiming in with a helping hand... but there are some issues even top techs have never heard of/experienced... we do not flog the hell out of customer cars! And if someone came in saying.. hey my car does this at 6k.... guess what. Could not dupicate. Period. We will not flog a cust. Car no matter what.