If you are going to drag, then sub frames are a must. Actually they are a must for just about every type of driving, let alone racing. Cheap subframes usaually have thinner metal tubing and they might not have the best weilds. If your really good with metal and have the tools, you could make your own for cheap. I have a cheap set for my 79 Daily driver and they really help the old body flex.
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1979 Mustang Ghia-302 HO @ 300hp, holley 600 carb, edlebrock intake, under drive pulleys, Bullet proof C4, 8.8 inch rear end with 3.55, Flowmasters Delta 40s American Thunder 2, pioneer head unit with sony speakers.
2004 Mustang Mach 1-281 DOHC @ 305HP, Shaker, 5 speed, 8.8 rear end with 3.55, Mach 460, Sat radio, Flowmaster Delta 50s, Clear Bright Fog lights, alum items for interior dress up, and an eject button.
i got some relatively cheap ones off ebay, maybe the same as those you show only in black.
i thought they are fine. welded on and nutted to the seat bolts in the center. theres a definate difference in ride feel, i guess its less chassis flex , less roll in corners, there maybe not the best sfc you can buy but they seem to work and are certainly better than going without.
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2003 Mustang GT. diablo sport tuner . CAI , 3.90 gears, Steeda Tri-ax shifter, BBK LT headers and magnaflow exhaust.
Yea, I have those sub frame connectors on my car. There cheap and work Great! There are 14 & 16 gauge steels that most common sub frames come in. These exact ones are 14 gauge I believe but the two sizes dont make any difference at all. After they are welded in they will keep the frame as one and get rid of all that unwanted flex. So for once a cheap item found on E-Bay really does work LOL.
yes blue oval makes them i wonder if i have 2 do anything else cause my car is convertible i have heard some ppl say they come w them and it doesnt say if there full lenght or not
ebay red subframe connectors 
Sub Frame 
