well that can go both ways. because if you were to stick bigger injectors in with out a tune they would still be pulsing at that set duty cycle. which means you most likely would be running pig ritch. An intake and exhaust will not make a difference in running lean. The mass air flow meter measures the amount of air entering the engine and monitors accordingly, and the ebp snsr measure the amount of back pressure in the exhaust and with other sensors would also adjust accordingly. but a tune will help make sure and possibly give you more power. also from my standpoint it is really hard to tune a vehicle without a wideband. some newer cars a equipped but that will tell you where you are running now......