Offroad-Express

I have bought a RD28T, which i will use to replace my worn out RD28 running in a MK2 Zephyr. My question is, should i go to the bother of fitting an intercooler?
There is loads of room to do it but is the gain worth the effort?
Also, what is the best type of head gasket to use? My old engine has a leaking head gasket or a cracked head causing one cylinder to miss at idle, but if i take radiator cap off and run car it is fine.

intercooler will certainly be an improvement.

head gasket, afaik only one type you can get for diesels.

Dont expect more power... expect lower egt's and the ability to have the engine under load for longer without getting hot.

Intercooler will give the engine more power.

The cooler air allows a denser mixture in the combustion chamber.

The denser mixture creates a better burn.

A better burn means more power.

Ask anyone that competes in Motorsport, they will tell you how much the outside air temperature effects the cars performance. The cooler the ambient air temp the better it goes.

Same principle can be applied to an intercooler. The Turbo compresses the air, the compression process causes the air to heat up way above ambient air temperature. The intercooler helps to bring this temperature down and keep the mixture in the combustion chamber denser.

As mentioned it can help keep engine temps down, but it's primary purpose is to increase the performance and efficiency of the engine by cooling the charged air down as much as possible before it enters the combustion chambers.

If I'm reading this right, you have a rd28 turbo and you want to know if you'll get gains from an intercooler against gains from NA?

I don't mean to question your IQ but fitting NA or Natural Aspiration to your turbo'd engine will most definitely not result in a gain unless the gain your after is engine longevity, fuel economy etc.
Intercooler on the other hand, like the others said!

I suspect you are just using poor English in your topic line.

^^^ I suspect it was used in a yeah/nah context... as opposed to NA/naturally aspirated. No more beersies for you!