The amount of deposits and borrows of each boost are determined by your initial deposit amount, but the LTV for each asset is always fixed. For example, if your initial deposit is 100 ETH and your boost is 4X, your total deposit is 400 ETH and total borrow is 300 ETH — 75% LTV. If your initial deposit is 1,000 ETH and boost is 4X, your total deposit is 4,000 ETH and total borrow is 3000 ETH — equally 75% LTV.