Theoretical power upgrades on a 5.7 gi

[twiggy2cents]

So I don’t really have plans to do anything but I was curious. My boat has a 5.7gi-c. It’s in a heavier boat, when running wot the last 1/8 throttle makes no difference. This is evident when I pull back on the throttle with no change.
Now I’m propped correctly and the engine is in good shape. I feel like it’s being restricted from breathing freely.
My thoughts are about what is restrictive on the engine? You think intake, tb? Exhaust manifolds are stock I’m sure that holds some back. Stock cam with stock ratio rockers.
Like I said I don’t really plan to make any changes but I was just curious if anyone had any insight to why I can’t feel the power difference.

 

[dypcdiver]

Have you checked at the manifold if the last 1/8 of throttle makes any change.

 

[twiggy2cents]

Good thought! I haven’t. The other thing I thought is if the tp sensor registers wot voltage at 7/8 throttle and the tb is close enough to wide open to make no difference. I will check the blade opening sometime though.