Trust me, it will make a difference. When external temperatures increase by 10deg i notice a difference in how well my car goes and ive got a SS cooler on there. Now think how much more heat there is going to be trapped under the bonnet than outside of the car.
You look at all the DERV's running hybrid turbo's. How many do you see using a set up other than PD160 with green filter? Very few if any. It's a proven solution.
Ok fair enough, I'm not going to argue with you Tom and your superior hybrid diesel knowledge...