Copper core plugs will work much better with our ignition system than platinum plugs. NGK BKR6E-11 or BKR6ES-11 are the preferred plugs for stock engines. Try using BKR7E-11/BKR7ES-11 with nitrous, and read your plugs every once and a while. If you find them fouling, go back to the 6's, if they are getting hot, step up to 8's. Driving habits will decide which heat range you need. (BTW NGK coppers are well under $2 each.)
Read here for short discussion on transmission oil coolers.
Transmission Cooler