I have never been a fan of the street cage idea, but if you do it make sure it conforms to the following rule set for the forward hoops.
15.6.8 Forward Hoops (Option 1)
The forward hoops shall extend from the main hoop (in a forward direction) to the floor
by following the roof and the “A” pillar of the car. There shall be a bar connecting the
two (2) forward hoops at the top of the windshield mounted as close to the roof as
possible without violating CCR Section #15.6.20 Inspection. The forward hoops shall
incorporate no more than four bends each. Optionally a “15.6.9 Halo Hoop (Option 2)”
or “15.6.10 Front Hoop (Option 3)” construction may also be acceptable.
15.6.9 Halo Hoop (Option 2)
A “halo bar” extends from the main hoop (in a forward direction) following the roof line to
the windshield then following along the top of the windshield, then following the roof line
back to the main hoop, thus creating a “halo” over the driver’s head. A “halo” bar shall
be constructed of one (1) continuous piece of tubing. One (1) down tube following the
“A” pillar must support the “halo” on each side of the car. The down tubes shall
incorporate no more than two (2) bends each.
15.6.10 Front Hoop (Option 3)
A “front hoop” is a bar that extends up from the floor, then follows the “A” pillar up to the
roof, then follows the roof line across the top of the windshield, then back down the other
“A” pillar, and then terminates on the floor. There must be one (1) horizontal bar
(following the roof line) connecting the main hoop and the forward hoop on each side of
the car. The front hoop shall incorporate no more than four (4) bends.
This is convertible to a legal cage: