Hey I'm new but I've been trying to find out how can i change my fwd to a rwd without spending over $10k and not a crappy design but something that will last under high hp

 

You'll have to fabricate everything, and purchase a donor car that has a rear wheel drive platform you can utilize. Even then, unless you're rather talented with a welder and can get materials for cheap... $10k is not enough for a rear wheel drive swap.