Consider a deresonated centre section, or a less restricted system depending on noise level. If you know your mot tester 😜you could decat the downpipe and uppipe to allow free exhaust flow. Look into a panel filter to help pre turbo breathing. And a fuel pump 😆😆😆 If you're on a td04 turbo that's pretty much all you need to reach the maximum safe limit of the turbo. Next would be bigger turbo and possibly injectors. Once all that's done, then remap 😈 Hope this helps