There has been much debate on the web about the actual amount of HP that the marine injectors truly add... with most folks going by the readings from their 'butt-dyno' in regards to how much power is actually added.
Simply adding different injectors WILL NOT increase power by 40+ HP, Period. The marine injectors have a higher pop pressure requirement, and numerous reports from users that tell of stock truck IP's killed by these injectors. You have to increase the pump pressure, and simply changing injectors won't help. This myth has been debunked so many times by reputable sources on 6.2/6.5 websites. Many guys will simply fall for the sales pitch of a company that advertises '40-hp gain
by using OUR special 6.X marine injectors!'
The 6.2 will not produce blistering amounts or horsepower in a naturally-aspirated fashion. The 6.2 stock injectors will flow more than the injection pump can deliver. The marine injectors require the marine pump setup to work, but it's like a light switch - boats are typically idle/ throttle wide-open, where trucks see a variety of throttle openings and speeds.
Yes - you can turn up the stock pump a tiny bit; beyond that, you're simply making smoke & less power. A good 3" exhaust will help the engine breathe. And clean stock injector with a good spray pattern & your pump in good working order will help.
Let's see some dyno readings, please.
BTW -
Stan's Headers, standard and custom high performance header designs for automotive and marine engines. offers 6.2 & 6.5 headers for sale...
'Tanner'