there is no template...it is trial and error.. the tubes need to be a specific lenght as well as routed properly.. this is why i had a chassis builder or someone who is familar with the math as well as the construction of headers.. it's not just putting some tubes together..what you build at home if done wrong could hurt your motor's performance greatly...lots of guys build them, but if you are not aware of what you need to be doing then you are going to do what i mentioned above..waste lots of time and lots of money buying header kits..they can be 300-500 per kit and if you make more than just a few mistakes then you are going to start buying induvial pcs or another complete kit trying to build something you have no concept of.. they is a science to tube lenght as well as collector size and then trying to get them all to fall out together with the correct lenght... GOOD LUCK !!!!!!!!!!!!