The ECU on my 2013 RT Ltd was up the front left below the LH headlight & under the frunk lid but behind the frame cross member, squeezed in below the 'remote battery connections' & in front of the engine between the 'cross body air trunking' & the frame cross piece the frunk hangs off, held in by 3 x 30mm long bolts that had to be un-done into a 20mm deep gap that could only be reached by someone with double jointed arms, triple jointed fingers, & flexible spanners - to put it mildly, it was a freakin' unbelievably inconvenient downright pig of a thing to get out; at least until I removed all the 'cross body air trunking', which then made it just a freakin' downright pig to remove!! I can now truly believe that the 2013's were originally intended to take the transverse 3 cyl motor but after all the ancilliaries & wiring were installed they decided at the last moment to stuff the longer fore & aft twin in there instead - the motor is waaaayyy too close to many things that it shouldn't be jammed up against, making them extremely 'inconvenient' to remove, & hence the excess heat trapped under the tupperware! Btw, I've left the 'cross body air trunking' off entirely & the ECU upgrade has not only completely removed the original '2nd gear hesitation' but also any potential flat spots that the trunking & air box removal may have introduced in any 'non-upgrade equipped' engines! .....snip.....