Like I said, you can bolt it in, look at the rule book. 6” square plate bolted to floor for the hoop, down bars bolted at floor and hoop, side bars swing out that’s bolted. Problem solved till you go 9.99 then you have a race car, period.

I have had both and like some said its nice not to be in the way. if you want to actually want to use the back seat how do they get in it. the cage if fine long as there only 2 of you.

"get away with" is purely at the tracks discretion, neither NHRA or IHRA would condone it as it violates their Rules and has potential to effect their liability and insurability (track and sanctioning body). And to answer your question, at my local track I have seen an occasionally on the first never on the second pass. The sanctioning bodies are very concerned with chassis/roll bar with this type of infraction.

This is taken from the 2021 NHRA rule book general regulations. It looks like the cross bars and rear bars definitely need to be welded to the main hoop. Be tough to get it in and out of the car if bolted to the plates on the floor.

4:10 ROLL BAR
All roll bars must be within 6 inches of the rear, or side, of the
driver’s head, extend in height at least 3 inches above the
driver’s helmet with driver in normal driving position or be within
1 inch of the roof/headliner in the area above the driver’s helmet,
and be at least as wide as the driver’s shoulders or within 1 inch
of the driver’s door. Roll bar must be adequately supported or
cross-braced to prevent forward or lateral collapse. Rear braces
must be of the same diameter and wall thickness as the roll bar
and intersect with the roll bar at a point not more than 5 inches
from the top of the roll bar. Crossbar and rear braces must be
welded to main hoop. Sidebar must be included on driver’s
side and must pass the driver at a point midway between the
shoulder and elbow. Swing-out sidebar permitted. All roll bars
must have in their construction a cross bar for seat bracing
and as the shoulder harness attachment point; cross bar must
be installed no more than 4 inches below, and not above, the
driver’s shoulders or to side bar. All vehicles with OEM frame
must have roll bar welded or bolted to frame; installation of
frame connectors on unibody cars does not constitute a frame;
therefore it is not necessary to have the roll bar attached to the
frame. Unibody cars with stock floor and firewall (wheeltubs
permitted) may attach roll bar with 6-inch x 6-inch x .125-inch
steel plates on top and bottom of floor bolted together with
at least four 3/8-inch bolts and nuts, or weld main hoop to
rocker sill area with .125-inch reinforcing plates, with plates
welded completely. Also, the roll bar may be welded to frame
connectors that are fully welded in place and are 1 5/8 inches
x .118-inch MS or .083-inch CM round and/or 2 inch x 2 inch
x .058 MS or CM rectangular. All 4130 chromoly tube welding
must be done by approved TIG heliarc process; mild steel
welding must be done by approved MIG wire feed or approved
TIG heliarc process. Welding must be free of slag and porosity.
6” max
All cars with an OEM frame must
have roll bar attached to frame.
Cars without frame use 6” square
1/8” steel plates on top and
bottom of floor, securely bolted
together with at least four 3/8”
bolts, or top plate welded to
rocker sill.
All materials must be 1 3/4” O.D. x .118” mild steel or .083”
4130 chromoly tubing, except A, which is
1 1/4” O.D. x .118” mild steel or .065” 4130 chromoly tubing.
5” max
4:10
A
Maximum of 6”
from roll bar to
driver’s helmet.
Maximum of 5”
from top of roll
bar to brace.
Section 21, page 22 General Regulations
Any grinding of welds prohibited. See illustration. Roll bar must
be padded anywhere driver’s helmet may contact it while in
driving position. Adequate padding must have minimum 1/4-
inch compression or meet SFI Spec 45.1. All cars running 9.99
(*6.39) or quicker, SFI Spec 45.1 mandatory.

I guess you guys crying about safety and a roll bar in the passenger compartment have never ridden in a Jeep?!

To be fair though, the cages in Jeeps and Broncos and other similar offroad vehicles are much further away from your head than a rollbar in a passenger car, and are also padded in the critical spots.

That being said, I've had a rollbar in a fox mustang before though and I never really worried about it. It's just a risk I'm willing to accept. I may eventually put a 6pt bar in my Fury but for now I haul enough people around in it that I don't want them to have to climb around the bars to get to the backseat.

Another question: I haven't installed my subframe connectors yet. If I put in a 6-pt. roll bar, are the connectors still useful?

Absolutely! They make a world of difference in a uni-body car!

If a track allows anything other than this to slide, it's between the "tech" guy, the track owner and his insurance company, if he has insurance. You can run there if you like. I have in the past and saw people get hurt over some dumba$$ stuff.

My CJ5 doesn't have padding. It is from 1980, though, long before everyone thought they had to have all the safety features in their driving appliances.

I like it, I had 73 CJ5

"frame connectors that are fully welded in place and are 1 5/8 inches x .118-inch MS or .083-inch CM round and/or 2 inch x 2 inch x .058 MS or CM rectangular"

I don't understand this. The connector provides vertical bending resistance.
The 2" rectangular is much stiffer than the 1-5/8" tube.

I fail to see the engineering that requires the rear tube to be welded to the hoop. A bolt-together design might be more expensive, complex, and heavy but easily made stronger than a weld. One method would be a flange-to-tube section welded to each of the main and rear, with a removable flanged tube between them. The attachment to both tubes passes already, and the shear strength at the flanges can be met by sizing the bolt area.
The welded area is the contact surface is (OD + ID ÷ 2) of the smaller tube × Pi × wall thickness. A 1-3/4" × .120" tube welded seam is .614 sq. in. 4 × 1/2" bolts provide .785".

Please: I'm OLD! Correct my errors, please.

I see the part in the rules where it says the rear down bars have to be welded to the hoop.
What I don't see is anything saying they must be one continuous piece of tubing. Make it bolt together say a foot from the hoop and carry the rule book with you. Done right it may be the strongest part of the cage. For sure it will be stronger than front swing out bars.

"frame connectors that are fully welded in place and are 1 5/8 inches x .118-inch MS or .083-inch CM round and/or 2 inch x 2 inch x .058 MS or CM rectangular"

I don't understand this. The connector provides vertical bending resistance.
The 2" rectangular is much stiffer than the 1-5/8" tube.

Please: I'm OLD! Correct my errors, please.