When I put my L16 in the racecar (not SR20 I know, but gearbox similar size ie. 63a stumpy) I didn't want to make it illegal for IPRA, we removed the original gearbox mounts so would not foul on the reverse light switch and also spread the tunnel a small amount with heat and a handle jack. Also massaged around wear the tunnel meets the engine bay, used a maddat ca gearbox crossmember which bolts through the floor.