after what else has been suggested if you still want more power and don't want to go efi then a fifth injector kit is the only other option. this should see you capable of upto 260bhp maybe more with the right setup. it's proper old tech as far as tuning rst's go but like i said it's pretty much the only way to go if you want to stay MFi. one other thing mate, ditch the dump valve. they're not only unnecessary but they tend to cause running issues like shit idle or cutting out due to vacume leaks. plus to be honest they just scream chav.