My cat on my camaro is 8years/60,000mi old when am I going to need to replace it? I've heard of the "rotten egg" smell that some give off, but my dad's trucks cat was shot & there was NO such smell.

The car has to be emissions tested soon & I wanna know now if I should replace the cat before it gets a fail (testing costs $24 each time)

 

You cat might be bad if:
1)Smells like rotten eggs
2)Glowing cherry red
3)Growling or ratteling noise from cat
4)Car seems sluggish
5)Car won't run (extreme case)
I wouldn't assume the cat is bad unless you have a reason to. I've seen two cats go bad, and neither of them smelled like rotten eggs, but both of them were making noise.