I have a 1965 Gt coupe It has a strong rust free body and frame, and a 4 point cage. I am in the process of building a 347 roller motor and expecting to put down between 400 and 450 hp to the ground. My question is, have any of ya'll put these kind of numbers down to the ground in an early mustang and what kind of chassis strengthening do I need to do? I have considered sub frames but am not sure if that is enough. THis car is my baby and I would hate to tweak the chasis. Any input would be appreciated. Thanks in advance

 

Tie the subframes for sure. How is your cage connected? Is it connected to both the front and rear subframes? If so, it should be fairly decent.

375 was enough to cause a windshield leak in my '71. Still need to get those subframes on...

 

Sub-frame connectors, export brace, monte carlo bar. All that will help from twisted the frame.

 

My 347 powered '66 chassis is fine with subframes, 4 point roll bar, Monte Carlo bar and export brace.

 

Cage does not connect both frames, gt comes with monte carlo bar and export brace. If I throw on some subframe connectors do u think it will be strong enough? Any suggestions on brand?

 

Lots of options on subframe connectors.
I have been happy with my Comp-Engineering subframes.

TCP has a pretty entensive subframe system with a "X" brace providing additional bracing if you feel its really needed.

 

Gt's didn't come with that stuff??? They came with a larger sway bar, thats about it. The monte carlo bar, and export braces came on Shelbys... and i dont remember if the export braces even did or not. NOW, Your car might have that stuff on there, because somebody put that stuff on there.

 

Gee how about front torque boxes

 

apparently u don't know much about the gt option but ok more to it than sway bars, u may be right about the monte carlo bar and export brace though, dunno. Bought the car 4 yrs ago with that stuff on it