Stove paint or on the real cheap grill paint. Much cleaning with mineral spirits first, followed by more cleaning, adhesion promoter, then the high temp paint of your choice. Cleanup is the most crucial step as any metal polish left on the pipes will cause the paint not to adhere...Allow a good long dry (at least a day) before baking the pipes (I just let mine sit at idle for 15 minutes then road the f*** out if it to bake em)
Several years of neglect and winter riding equals.....