Have you ever wonder what that round bubble at the end of the header looks like inside?

 

inside look....

 

oh, sorry.. this is the header for the SC300

 

of course its restrictive, its a catalytic converter. You have a few options. Punch the cat out, which in some cases decreases horsepower and torque (not sure on this one). Two, buy an aftermarket header for the NA supra. Three, leave it alone.

 

Putting a better flowing cat downwind of the header is a better solution if you have to smog.

 

Yup... I replaced an aftermarket header. Now, it pulls a lot harder from low to high RPM. I can really notice the difference more so with this mod alone than the MAF cold-air filter, the Greddy MX exhaust system, and a full service turn-up combined. It has a very quick response...