I Still have the intake manifold from my Tj, I have read that there is a small HP gain in doing the swap on older 4.0 liters but is it really worth it?
iv done the research about this swap and i don’t think the gane is worth the time and money to swap.but if the engine was coming out or needed a intake gasket id do it.
I agree with matt. If the swap is done alone in and of itself, there are varying results reported.
However, If you port match (correctly) and add a 63mm TB, then you will see some gains.