If you're a do-it-yourselfer, you might try techline coatings. I've used both their satin black and cermaic chrome with good results. Requires sand blasted surface prep only. The black did not require oven post cure, just successive heating from exhaust heat. The silver chrome requires post cure in oven but can be polished afterward. Both can be applied with conventional painting equipment. I'd still suggest shipping off your headers however for professional treatment if your pocket book cna stand it. -They get coated inside and out at the pros. Mufflers are more problematic in this regard.
techline coatings
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.