will it fit good ? and how much mods will have to be done to get it to work in my st204?

I believe there has already been a bunch of posts about this. Do a search and you'll find plenty more detailed info.

If I remeber right it will bolt up right just there is a clearance issue with the downpipe. Just search and you'll find out.

I think it's halarious how we found out this thing actually works. People kept saying it wouldn't work, and it's been established that it won't. And it's too much work to try and make it work. Then, someone does it and we find out all you have to do in modify the downpipe a little.