I'm looking for anyone who can give me a before and after impression of adding bolt in door bars to a car that already has a hard top, roll bar and frame rails installed. I heard good reviews from people who just have a door bars but I'm curious how much it could help me and if its a worth while investment.

I don't have frame rails yet, but it's on my list. I do have a hard dog xtreme roll bar, and a hardtop with front and side latches. (Some people only use the Frankenstein bolts and the front latches). The day I installed my door bars I noticed a difference. It's similar to adding subframe connectors, except they're not under the car.
I am 6' and it does make the car more of a pain in the ass to get in and out of, but I really like em.

94 with Hardtop with top and side latches, HDHCDD roll bar, Frog arms, and the door bars. No frame rails yet.

The door bars made a noticeable difference. I heard a couple stories that door bars are far superior in adding stiffness then the frame rails would be so I opted to go that direction. Even with the hard top off I get virtually no 'miata shimmy' that was sooo aggravating before.

There are a bunch of threads about this.

Miata Turbo Forum - Turbo Kitten is watching you test compression. - Search Results

I opted for door bars before frame rails because I heard they were more of a difference. I still want frame rails though just for better jacking.

No hard top... but I do have the frame rails and door bars with Hard Dog roll bars.

The door bars make the car VERY stiff. It tripods up and down angled inclines now.
The Miata without the door bars will not... even with the frame rails it twists...

The bars aren't very intrusive either. Definitely worth it. Can't wait until I put door bars into the second Miata as well...

Door bars for stiffness.

Frame rails for protection. I'd never track it without added frame rails (i.e., scuff plates).

If you use FM's frame rails, do not use their brake/fuel line attach points. Build your own and get them snug against the floor and well-protected.

YMMV.

I had the frame rails first then added hard dog door bars. didn't notice any difference when I took the frame rails off and left the door bars on. the door bars add about 98% of the stiffness benefit between the two I believe.

Door bars or frame rails arn't legal in any SCCA solo class besides XP.
It's a lot easier for me to un-install and reinstall door bars than frame rails.

Thank you for the input everyone. It looks like door bars will be in the build plans for the near future. :bigtu: