Pricy but very effective. The stock cooler is pretty good though whenever i buy a used one they have all been clogged or what not and dont make any oil pressure.. likely pulled from blown motors, so be wary of ones you find on ebay.
Stock has been fine for me in 105 degree TX summer heat, temps get up to 200 is all. It's all about the ducting and airflow.
I have read great reviews of this place http://www.americancooler.us/ which is FAA certified and cleans oil coolers. I sent them a cooler after I spun a bearing, they tried to clean but could not get all the particles out and did not charge me. I just sent them another cooler to clean a few days ago. They can also X-ray the cooler if you want. Get a used one with good fins for $50, then spend $100 for cleaning and you have a just as good as new cooler.