[Smoove]

Originally Posted by hansj3

oh and FastPlastic the 4.0 had a cool mod involving th intake manifold out of the 99+ wj's.
Swapping to a 2000 Inlet Manifold

I swapped out the manifold and injectors on my ZJ from a 00 XJ, and I wouldn't recommend it. It wasn't a significant expenditure of time, becuase wrenching with friends allowed me to swap exhaust manifolds in under three hours, and the cash outlay wasn't bad ($150), but the gains were simply not there. It increased my 0-60 by .01s, my mpg by.2mpg (measured at 0, 500, 1000, 5000 miles) and no seat of the pants gain. The manifold was designed to use airflow more efficiently under 2000rpm's, and is suspected that it needs the matching head and internals to see the "15hp) gain.

YMMV