No, It doesn't stiffen up the chassis. I would recommend the stiffening brace from eyeballengineering.
http://www.eyeball-engineering.net/F...stiffners.html
Or, you could fabricate your own. Here's one I did from 1 1/4 " square tubing...
The clips I got were from Vee Dub Parts Unlimited in Huntington Beach, Ca.
https://www.vwparts.net/Merchant2/me...y_Code=CHASSIS
Good Luck.