The Racing Beat Race Exhaust Port Templates for all 13B engines allow you to undertake your own exhaust porting modifications. The race version of these templates open the exhaust port further "upwards", increasing the port timing duration which results in more intake-exhaust overlap and better high RPM performance. These templates are traced from Racing Beat's own master templates, which are the result of years of research and development. The actual port shapes are traced on thin sheets of aluminum which you must first cut out, testing your ability to use a die grinder effectively before attempting to port an expensive engine component. The finished template is held in place and the porting shape is then traced onto each housing. You must then use your own judgment to develop the port shape beyond the scribed line.