Hey guys I'm new to the scene. A friends brother owns a 99 eclipse gst that I will be buying next week =D. Once I get it I will be posting pictures and I'm hoping an upgrade path of how I want the car to turn out. I've been stalking the forum for a few weeks now and decided to make an account today =)

Congrats! ( in advance). You'll be looking to awd swap her within 1 year hahaha, but still, a fwd pulls like a mofo. No question about the roll-ons
You got the best gst possible IMO: ITs the newest. Less years on it and probably less miles. Mine had 199 when i bought it. No rust though, very lucky.

She has 165 on her. The only rust I saw on the body was under the hood on a circular piece towards the back of the engine, right above the suspension. She is an automatic and I was planning on swapping it to a 5 speed eventually.

That sounds like strut tower rust, it's common but it's not good. You'll have go take care of that asap. Good luck I'm a fellow GST owner I enjoy mine.

I've heard I can either spray paint over it to stop the rust or get the piece completely replaced, can anyone tell me the downsides of just spray painting over it?

Good luck on acquiring the new DSM. If that doesn't work out, feel free to PM me as I have a couple I'm about to sell that has absolutely no rust(I'm the original owner and live in Florida.) I'm no paint and body guy, but spray painting over rust? To me, that's like putting a Snoopy band aid after just getting 3rd degree burns from blowing up my arm. Fix it right and do things right the first time. You'll have less headaches in the long run if you stick to that theory.

surface rust is easy to take care of, just get a steel brush on a grinder or air tool (or by hand(old school) clean it up and then paint it. painting over rust will make it look better but wont fix it, it will continue to rust and eventually you will have a hole where a rust spot was.