So I made the mistake of buying a grow tent kit(first time grower, obviously lol). It came with a weak ass 300w led light that I honestly think is the reason my plants aren’t thriving like they should be. Since then I have already invested in a Mars 1000w led. My question is will it significantly ruin my yields if I switch lights or do I just need to suck it up and use this light for this grow?
Use the Mars. Your plants will love it. You could always dim it if necessary.
Your plants will definitely thank you and it should show within a week. It won’t decrease yield at all just increase for sure. Happy Growing 
Just go for it, they will appreciate it.