I am working on an R56 franken-project right now. I bought a 2008 base model for a whole $500 with a blown motor and I've been fiddling with it with the idea of making a fun track/autocross car. Being an 08 it has an N12 but the motor is shot, timing chain jumped and although I haven't pulled the head I'm sure there are some S shaped valves as the crank and cams turn completely independent of each other.

Since I can't stay off ebay, I just found a low miles N16 out of a 13 that I'm going to drop in. My understanding is there are some differences in the oil pump between the N12 and N16 but other than that, they're pretty much the same. I've found that they use the same head even.

So my question is, why in this listing for an OBX header do they say it only fits up to a 2012?
https://www.ebay.com/itm/OBX-Exhaust...-/153404295184

Even further digging shows that OBX only claims it will fit up to a 2010.
http://www.obxracingsports.com/products.php?pk=1770

Is there any discernible difference? Clearance issues? Or is this just a case where us Justa Cooper owners know more than the manufacturers? I don't see anything that would make this not fit aside from maybe the oil filter housing if that's different on the N16. Anybody have a clue out of the dozen or so base owners who like to mess with cars?

 

That header will likely fit up just fine. It is likely OBX just not doing their due diligence for compatibility. Wouldn't be the first time... They have a header and exhaust for the NC Miata, too, but only list compatibility for 06-08 model years, even though the exact same engine and exhaust is used all the way up to the 15 model year. Cheap company, low research budget.

 

OE part numbers will likely have changed due to emissions, which could be accomplished by increasing the content of precious metals in the catalyst. That likely doesn't mean there are differences in fitment at all.
To give an example: Euro spec Justa-Coopers met Euro 4 up to 2010 model year, LCI had Euro 5 and the 2013/2014 MY even met Euro 6 standard. I doubt they could do that without some hardware tweaks (and just by altering software instead).
It could be similar on NA spec Justas.