The heat coming off my headers warms the passenger compartment a lot. I have the floor and back of the firewall insulated but still gets warm. Rather fatiguing on a 600 mile trip in 100 degree weather. I've never driven this car with anything but these headers so I can't compare the heat what would come from stock exhaust.
I had that on My Alfa Spider, but under drivers floor (exhaust header pipe goes on drivers side , 4 cyl) ) ....very uncomfortable....but installed header "wrap"...it helps quite a bit!
