I have some pretty bad leaks on my exhaust manifold. I plan to upgrade to headers and a new exhaust to fix the leak, gain some power, and improve the sound of my fastback. I still have my original cast iron heads. In a year or two I plan to upgrade to aluminum heads. Is there any issue putting new headers on now and upgrading to aluminum heads later? I’ve heard there can be issues accessing spark plugs sometimes... although I think the AFR 165 heads I plan to use won’t have this problem. Will the headers warp and leak if I try to swap to aluminum heads later?