taken from the link chris provided:
KAMIKAZE HEADERS
Over the past 15 years Kamikaze's Research & Development department has been dedicated to revolutionizing the racing industry. Prior to Kamikaze's 4 into 1, 1 3/4" two piece header, there were only two options in the market. A 4 into 1 full length header and a tri-y, 4-2-1. The mistake of the 4 into 1 full length header is that the primary tubes are 1 1/2" 16 gauge diameter in size and the over all length is approximately 30". With this design you have less torque, mediocre on mid range and weak on top end. Due to the diameter of the primary tubes are too small and too long in overall length. Further, installation is extremely difficult and you need to relocate the 02 sensors.
A Tri-y 4-2-1 header did help in the early 80’s but when cars began to have more horsepower and torque. The Tri-y configuration were found useless and out dated for today's compact cars. A Tri-y header was never designed to be a performance header. It was originally designed for a truck. That needed the torque for towing. Which also fails miserably at top end. You never see a tri-y header on a dragster or any professional racing vehicle.
You can truly say that Kamikaze stands alone, this is not another clone!
Kamikaze has used the latest technology available to construct a true racing performance header. Kamikaze has constructed a 4 into 1 header that fits stock location. Kamikaze utilizes, 3/8" laser cut flanges, 1 3/4" 14 gauge, mandrel bent primary header tubes that are engineered at just the right length to give you a great response in torque. Our 2 1/2" collector, is designed with the primary tubes joining as they transition into the collector to give more precise management throughout the mid range, The 02 sensors are located at the proper location to read off all cylinders, based on OEM style. Kamikaze went further in constructing a 2 1/2" secondary pipe which maximizes the level of back pr