Bypass the radiator cooler is the best option. Running them inline you still run the risk of cooking up a milkshake when the radiator cooler fails. I also suggest you flush out the oil from radiator cooler, spray carby cleaner in the upper passage and flush with water, then plug it up with some bungs. This will ensure that if it ever does fail, you coolant will not mix with the tranny oil left in it and also will not leak. I got a oil temp gauge on mine and it runs at about 50 deg C on the open road, about 60-65 deg C in heavy traffic and I have never seen it go over 75 deg C when giving it a hard time. This is much cooler then it would be with the radiator cooler.