About how much horsepower should I increase with if I install a LT4 intake manifold, ported for a 58mm throttle body, with intake runners fully ported to match Felpro LT4 gaskets?

I was also thinking of installing an Lt4 Hotcam profile Camshaft that is polished, about how much horsepower should that give me also?

 

Bump.

 

Nothing. Because if you install a LT4 intake manifold on your car with stock LT1 heads, then the ports won't properly match up. But if you are running LT4 heads, then you might see a slight increase.
Good luck

 

There is also no reason to run a 58mm tb unless you have enough work to require it

 

What mods do you already have?

Unless you've got a cam, ported heads and all the other bolt-ons, that stuff is not going to be worth your money yet.

 

I dunno why people keep sayin that. My SS has a SOTP HP increase the throttle response is crisper and quicker. It's pretty much stock,still has the manifolds. Only dynoed 289 RWHP befor the Holley 58mmTB.

 

The throttle response increase is because the bigger bores allow more air with less pedal input, your WOT numbers will not have changed greatly since the stock TB can support a stock motor pretty well. A ported LT4 intake on stock LT1 heads is going to be something less than worth the effort, heck the LT4 intake requires work to even make it fit LT4 heads right.