It'll have to be liquid heat. There isn't a provision for air.
That said it really works well and woke my engine up significantly. I had pretty much exactly what you have. You'll also need to either mate to the existing exhaust or make a new one. I went with bringing the two together downstream and running a single 2.5" exhaust through Flowmaster 44's. She sounded really good but it'll cost you about a grand once you're all done if you pay an exhaust shop to do the exhaust.
Also consider a mild cam at some point. After that the only non-FI things to do are lump ports, HEI, electric fan, etc. Try to take some load off the engine via the electric fan. The mechanical fan draws a lot of power up top. Another option is a fan with a clutch. That way it's not drawing so much power at the upper RPM's.
Short video clip of her driving away the last time I saw her:
https://www.youtube.com/watch?v=lJdZDW0AiO8Sad moment for me but you get a good feel for the exhaust sound.
You can see how I routed the coolant lines here:
https://i.imgur.com/wgDOX0i.jpgNotice the brass T's at the fire wall. I T'd the heater hoses to get some flow over to the intake.
Missing some pics but here's another:
https://i.imgur.com/iMmgB2s.jpgI made a flat plate that I put two taps into for elbows and ran the heater hoses to it. Had to made a gasket from rubber and used a ton of RTV to seal it. Had to re-do it 3 times before it sealed but once done I never touched it again.
One other thing about the cast headers: the flanges are a different thickness than the OEM manifolds. I had to grind off some of the spanners to equal things out (I mean the things that hold the flanges on via the studs in the heads). Not a huge deal but still something you'll need to do.
