I have a 69 firebird 400 convertible. I am looking to add rigidity to the frame and reduce flex.
Do you recommended sub frame connectors? What are the drawbacks to doing this kind of modification?
Would Hotchkis sport suspension sub frame connectors be a good choice?

I have a set of bolt-ons but haven't installed yet.

Perhaps more info in the Body section of the forums?

I put on a set of weld-on. They only weld on the front. I don't know why, I suppose I could weld the front up sometime. If I did it over I think I would use the bolt ons. I was doing something under there a while back and they got in the way.
They do stiffen things up. They also recommended using solid body mounts with the weld-on bars I got. I bought a set of aluminium bushings with the bars, they really reduce sway on cornering but if I run over a peanut I can feel it. Way less damping of road vibration and jarring with the solid body mount bushings, good for racing though.
If I was going to make a recommendation, which I shouldn't as I get myself in trouble that way, I would suggest bolt on bars and non solid bushings for a stiffer but not too harsh street ride. Racing is a different cup of tea.
Just my opinion, I could be wrong.

Mistake! Mine only weld at the rear, bolt in the front.

Do you have a link to the ones you bought Bluebird??

Not sure if the conv brace has anything to do with fit but SFCs are a great upgrade. I would think even more so on a vert. Mine were Comp Engineering, IIRC. I do a lot of work to mine so I am glad I have the bolt-in version. I've had to remove them a couple of time for one reason or another and if they had been welded in...well it would've involved alot more cussing and throw things. Just my $.02.

Long old discussion of subframe connectors:
https://firstgenfirebird.org/forums/ubbthreads.php?ubb=showflat&Number=250290&page=1

Interesting this old topic closed with a discussion with Firebob back then, about whether or not, or where/how exhaust would fit with my custom weld-in SFC setup and my integrated drop crossmember all in the way. To bring closure I will share that my favorite local muffler shop custom-bent and welded up a dual 2.5" with crossover system and it fit right into the tunnel alongside the driveshaft with no problems whatsoever, and my convertible brace still fits in the correct place with no spacers. They charged me $267.50, all parts & labor included. Nothing bumps or rubs or leaks. They did the whole thing while I watched inside of about 3 hours. It would have taken me 20 to 50 hours to do what they did. That sure cured me of ever considering doing my own exhaust work ever again. I couldn't have even purchased the parts they used for less than $300....most similar "kits" are in the $450+ range. I'm a big DIY guy normally, but some things beg to be subbed out to people with lots and LOTS of practice and experience doing their one specialty, and a tightly/complicated routing of an exhaust system is DEFINITELY one of those things. I'll never touch an exhaust pipe again, as long as this shop is still in business....

Now 2 years later. No regrets. The weld-in SFC's were one of the best handling upgrades I ever did on my convertible.

Great info. Now if we could all go to Indy to get it done it would be great. Sounds like you found the shining star in muffler shops. Last time I needed tailpipes installed they put the car on the lift, raised it up, looked underneath, lowered it down and politely asked me to leave. The one after that just looked under the back and laughed and told me NO! And that was just tailpipes!
Like I said, I mess with the car ALOT so bolt-ins work best for me while I admit that weld-ins are a better option for most. Actually I don't think I've ever seen a pic of them welded in place. Can some one post a pic?

I don't know how to put up links, I'm better with a wrench than a computer.
Mine are Global West.
And yes there is a lot of cussing when you can't take them out when messing around under there.
I needed to have my exhaust run behind the axle to get my import inspection passed. I went to a muffler shop to have them install some pipe back there. They cut off all the hangars and installed new ones by drilling into the frame and through the floor behind the seat. Charged me $450 and one side fell off two weeks later. I want to go to the shop Crazy used next time I need an exhaust done.
I have pics somewhere hidden in this Voodoo computer thing, I'll post if/when I find some.

Well since they're just a hop/skip/jump from California AND Canada...I'll post up their contact info...LOL...

Mufflers & More, Noblesville, Indiana. 317-896-5868

Looks like the Google reviewers seem to like 'em too:
https://plus.google.com/106603966381333792939/about?gl=us&hl=en

Best little local budget repair shop I've ever had the pleasure to deal with...they'll fix anything, but budget exhaust of respectable quality is their true specialty...

I wouldn't take 'em a concourse job, but for strong/functional/quality/basic exhaust systems for a REALLY low price and no-questions-asked-stand-behind-their-work-folks, they simply can't be beat.

Surprised theres no shops in Cali.
There's one across the street from where I work. And another 2-3 minutes down the street.
Both use raw stock and bend to fit. Any car/any truck.

69byrdfan, sorry to get off topic. I hope you got your question answered.

I'll need to have the exhaust redone again after I put in the four link. It might be a good idea to drive down to Indiana to have them do the job. May run into a few Firebirds on the way.

Oh there are shops, but GOOD shops are few and far between...anywhere I suspect.

Hey Bob, we have a great muffler shop here in Petaluma. They are reasonably priced too.

Thanks B. Good to know.