I've heard that the bar with the curve in it (to avoid the air cleaner) works as a great big spring and doesn't help stiffen the chassis. I've also heard that the straight bar is the way to go if you can get it to fit.
Are these facts true? I haven't a clue. Seems like good questions to ask someone with lots of handling experience, like Vic Yarberry at Cougars Unlimited.
I just installed a curved bar on my 69 convertible with 351W, I started to go with the straight bar but it wouldn't clear the distributor. In my opinion it has stiffened the ride a little, the ragtop doesn't rattle as much as before and I'm glad I added it.
Yes Logan it is a very cheap and practial upgrade which helps stiffen the cougars unibody and will help deflect flex in the shock towers especially in the 67/68 models. It also helps with tourque flex from high powered engines such as a clevor. now as to the question about spring back or tension load on the curved bar. yes your right jim it does by its design flex but for the average street driver the amount you get is so minimal that you wouldn't ever notice and it sure is better than not having one. Now there are the inexpensive ones like leon has on his which for all practical purpouses work great then there are the race and tuneable type which are quite a bit more expensive but they can be adjusted for trans am racing or drag strip, great for bragging rites but for the average streeter thats about all they are good for since your car is never pushed to those type of limits. I suggest since the run 14.95 for black straight to 24.95 for chrome curved from mustangs unlimited it is cheap insurance on not cracking a shock tower. they also have a a tcp bar for 134.95 page 86 of their catolouge.
I put export brace and straight monticarlo on a week ago and it feels much tighter. The monti carlo bar was fun to install ended up with 31/2 LB hand sledge to nudge it and aline flange to shock tower.
I had jacks on each motor mount and still had to nudge monti carlo flange. The angle of flange didnot matck inner fender wall and shock tower. Jacking did help greatly with export brace to aline holes.