I am likely about to order the 5/16th plenum spacer. I have seeen the dyno charts and they look good. I have a question though. What is the actual difference with the iso thermal modifications. Are they worth the price difference. Can someone explain this for me please.

 

yes it is, the iso thermal keeps heat from the engine head to your manifold (aka plenum). This will allow air up to 70 degrees cooler - a TRUE cold air intake. After MANY hard runs even a pull on the drags i'm able to set my hands on top of the intake plenum, no problem. while my friends is hot enough to make a nice warm meal

The ISO kits includes a thick gaskets that goes below the lower plenum, plastic supports that does not absorb heat, a valve to stop HOT coolant from heating up the throttle body (or you can purchase the copper throttle body gasket that'll allow the throttle body to warm up with minimal heat soaking)

 

i wanted to know the same thing. good question