I got a TP EFI, i want to increase performance if i fork out for a set of extractors, new exuast and muffler system am i going to notice any significant changes, maby if i add a K&N Pod filter aswell? and can anyone recommend the best brands and what its likly to cost?

i had 2.5inch cat back zorst and extracotrs on my TP elante back in the day....... didnt notice much more poer than a standard TP