I am going to put some Progressive 422's on my 04 Fatboy and am going to set it down about 1.5 . Question is should I do the front as well ? What are the Pros and Cons if any ?

 

You can end up with some front end flop if you only do the rear. It's more nuisance than anything. The front wheel may progressively want to fall to full lock left or right. The lower you go in the rear without doing anything to the front, the more you will notice this.

Lowering the front usually occurs with a Progressive spring kit or similar along with some heavier fork oil. That usually combines for better performance in the suspension; less nose diving on hard stops, better cushion over bumps, etc. Plus, you can keep the geometry consistent with the lowered rear.

 

Yes! At least 1"

 

About 3 weeks ago I lowered my back end about2 inches with 422's on my
05 Fatboy (my sig picture is pre-lowering). I perfer the angle of where it sits
w/o lowering the front on the fatboys. This of course is of personal taste. The flipside of this,
is that the geometry of the bike is different. What I mean here is that the handling
is different. How a bike handles is subjective imho, so to me it was'nt a big deal,
just a learning experience. Let me know if you want any further info.

 

Over on the Night Train thread almost everyone has slammed their bike. Only a few haven't lowered the front. Those who haven't are planning to do so. I just did, and it seems like the front seems to handle much better than stock.

 

If you must lower it, do both. I had mine lowered for a couple years and my advice to you would be DON'T !! But that's me. I had 422's on there too. It still rode like a Buck Board. After one long ride, they were sold on ebay. I bought em at a discount so I didn't loose my a$$ on that one. I have put it back totally stock. It rides the turns better and handles the bumps WAAAY better. I preffer the better clearance, not that a Heritage is great out of the box. But I do actually enjoy riding it again.

If you are going to lower the front, I strongly recommend NOT using the Harley kit. It is JUNK!
Bottoms out on everything. If you hit even a small bump while on the front brake, it will bottom out. White Bros or Prog Susp makes a firmer more progressive kit. Use those.

Remember too, a Nightrain (or any FX) is 3" taller in the front, so when they lower em, they going to (stock) FL height. And yes they do look awesome lowered.