I honestly never noticed a difference. I have never drove it without a spacer. I admit my vacuum system has been completely reworked. But still functions as it should. It passes smog so I'm happy with it. Funny thing is it passed emissions with 1-2 and 5-6 injectors being in the wrong order and I had just got it running after a head replacement the day before.

 

Bought my first Jeep 4 months ago. 2000 Cherokee sport. I love this vehicle but the catalytic converter setup is horrible. The only positive is that the exhaust system is much more home mechanic friendly than most new vehicles. Frankly I think all manufacturers should make converters easier to replace considering how much it costs to replace them. If you have a vehicle over 15 years old factory converters cost almost as much as the blue book forcing many people to junk vehicles that still have a lot of life.