I replaced the starter and battery and when trying to start the car the 30A starter fuse keeps blowing. I also replaced the 2 relays in the fuse box. Any suggestions?

 

Disconnect the negative battery terminal and then follow the main power connection from your starter back to your battery and make sure it isn't touching anything. Especially the main wire coming off your alternator. If those are good check that your starter ground wire has a good connection. OR that the engine grounding strap is connected properly. It's hard to overpower the starter unless there is a direct short or unless the ground is weak and it's causing the voltage to spike because it's drawing a bunch of power and trying to return it through a narrower than necessary ground connection. DO you have the T5? IF you do on the drivers side there is that empty space behind the headlight, there are a couple grounds bolted down right there you should take off and clean good with a wire brush, they corrode eventually if you live somewhere it freezes a lot and they put that crap on the roads to melt the ice.
The grounding strap is located on the back of the engine up top on the passenger side. It looks like a woven wire strap. If your starter grounds through the engine and the engine has a bunch of corrosion there you might need to clean it off and put the starter back on. I'm assuming you have the T5 white block, that's all aluminum.