No. 99-current Mustangs do not have spark plug wires.
You just need to buy plugs. Do a search on the horror stories on spark plugs blowing out. I left mine alone. I didn't want this to happen to me. If it runs fine, I go by this saying:
If it ain't broke, don't fix it!!
Are you running the stock plugs and stock gap on your blown 96 Cobra?
The platnium plugs are good for 50K miles. So, at least at some point, why wouldn't you want to chg them? Although there are some have had issues with spark plug blow-out, weren't the threads lengthened by 2002? Nonetheless, if you are careful and keep in mind that these are aluminum heads, you'll have no issue. Clean as you go, use anti-seize.
I'll tell you what I did on my first plug chg - I don't do this anymore, but I think it helped initially. I run copper plugs (shorter life, cheap, better spark conductor, plus it gives me the chance to inspect what's going on in the combustion chambers every 6 months or so), and chg them every 6K miles. (On the 4V, it's REALLY easy to do, but the 2V isn't too hard either)
OK, what I did was this: lube up the threads (anti-seize) on a new plug pretty well, not excessive though...you don't want a bunch of that stuff dropping down into the cylinder. Thread the new plug down into the head using approx 18" length of fuel line (push the terminal of the plug into an open end of the fuel line, then guide it and turn it with the other end of the line). When the plug terminal begins to slip in the fuel line (caused by meeting resistance in the threads), back it out. Clean the threads thoroughly. REPEAT. REPEAT until you can thread with the fuel line to a comfortable depth, then cinch it down with a torque wrench (or a regular socket will do, but BE CAREFUL not to overtighten - you just want them snug) I use a 1/4" socket wrench (rather than the larger 3/8" or 1/2") to help prevent overtightening.nother tip - I use 3 finger tips and a thumb to tighten. Regardless of the wrench size you end up using, don't grab the wrench like you're taking apart suspension pieces - with a full palm / fist style grip. Gently hold and operate the wrench - that'll help.