Strip it. Back seat, door panels, headliner, spare tire, AC, power steering, console, cupholders, glass (replace with Plexi), chip it, cold-air intake, take the carpet out, etc.
I've gotten rid of a couple of hundred pounds in an old E30 this way. Works great!
Yup, but never had any mods. It was a stock '91 Golf Wolfsburg, red, with teardrops. I loved that frickin' car. Just left me on the side of the road too many times and my minimal experience at the time couldn't keep up with its demands.
From my understanding the internals are pretty robust so it should handle a 50 shot just don't go higher than that.
You best bet however is to go turbo. I'm working towards that goal myself and I have most of the parts. Just need a down pipe and a custom turbo header. I'll be using the T25 from the Mazdaspeed Protege.
Tow it behind an F350 w/a bullydog comp. No seriously, boost it. It's what I'm workin' on doin' to mine. Upside-stock motor is stout and can handle boost no prob. Downside-drivetrain is weak and not upgradeable. From what I've researched 200hp seems to be the most the drivetrain can take w/o grenading 3rd gear routinely. If i'm wrong I hope someone can point me in the right direction as I would like to go bigger on this lil' motor.