Before this, remember that the original non-S muffler is TERRIBLE for power. Mine I cut the top off and modified the internals-instant power gain. Now, the rest of the story. I will port my head, then get a chip that raises my shift points on my cvt auto trans to 6300rpm (I don't know how much rpm this engine can deliver, so I'm going conservative), to take advantage of the increase in airflow at high rpm. It seems that most port work helps mainly at high rpms. I had ported the head on my Datsun 240Z, and it now has race-winning power from 4500-7000rpm. With our little 1.6 liter engines, good heads and rpms are the way. If someone else has already said this, then consider this post a confirmation. My hobby is making slow cars fast since around the year 1980. My Mini is a slug, but not for long! -Jeffy.

 

Interesting. I'm curious how the cvt tranny will handle the additional power and being driven hard. My first MINI was a Cooper w/ CVT and no matter what I did to the car I never saw the extra power as it seemed to stall in the tranny.

 

As for the cvt handling power, I studied it's design from ZF. It seems that heat and breaking the drive belt are limiting features-so, from soon after I bought the car, I changed the trans oil for a mixture of 50/50 ATF and synthetic motor oil. My tactic is to let the belt slip rather than break, and using the fluid combination I have, the heat won't break down the lubrication. I'm over 50,000 miles with no trouble with the cvt, though it does slip on an aggressive launch from standing still. I do want instant down-shifts, though, so I will be talking to MTH. -Jeffy.