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I just want a good handling car for the least amount of money.
Sorry but I don't know about g numbers. I want to be able to compete against other classic racing cars such as AC Cobras.
Is it possible to do that with original k-frame and leaf springs?
Anyway, I want to stiffen the chassis with the parts from XV. Will torque boxes do any difference upon that?



Well, g numbers are a start to quantifying the actual "handling" performance just like e.t. or trap speed quantify straight line performance. This is important to know, because "good" handling is very subjective to many people. A lot of guys think their new Accord is great handling. to others, a Viper is a great handling car. I'd put it something like this:

.6-.7 stock muscle cars
.7-.8 econo cars
.8-.9 average modern car, slightly altered muscle cars
.9-1.0 modern performance coupes & sedans, significantly modified muscle cars
1.0-1.2 is getting into mild competition territory
1.2 and above, super car and the start of serious competition range.

If your competing against AC Cobras, then sanctioning body and class rules will dictate more of what you can and can't do than anything else. Not sure where you would be running against these guys, but your already at a big disadvantage when it comes to weight and geometry. You can overcome a lot of this if you are a good enough driver with a very well thought out suspension, but against a good driver your probably toast.

In any case, yes, you can still get a lot of performance out of the stock K frame and leaf springs. Just be prepared to do a lot of work to get things dialed in. The biggest problem with a stock suspension mopar is you can only go as big as 1.22 in the t-bars. This limits you to 400# of wheel rate, which could become a liability in serious competition. But, if your still wanting to get after it, you can build a very stout set up. The cost will depend on your scrounging and fabricating skills. My set up was only around $1500, but I haven't added the shocks in yet. I could easily double that with just the shocks. For most, the XV level 1 kit is a great starting point for significant road feel improvements and reasonable ride quality. To piece together a similar set up would cost you about the same dollars and you still wouldn't have the perfectly matched shock/wheel rate combo they provide. Cost to benefit ratio is also an area with wide variability.

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you wont be re-inventing the wheel here, but IMO, trying to make a 40 year old car handle like a new car is a loosing battle from a $:performance ratio.



I'd say this statement is one of those "it depends" situations. Like I said above, the XV1 kit can get you into modern territory for $2500, depending on where in the "modern" range your shooting for and where you want to draw the line. $2500 seems reasonable to me, but to a number of people, the $7500+ of an AlterK is reasonable but the $10k of an XV2 seems unreasonable. Again, it comes down to driver's perception and intended usage against budget. It is never as simple as "make my car handle great." Great has many different interpretations and budgets.

Do torque boxes help with additional stiffening, yes. Sorry I can't quantify these numbers, but I've never measured them. The video on XV's website is probably the best reference you can find for stiffening. The torque boxes are tieing in the rocker area, which is a very strong tubular structure on a mopar. This is an are not directly addressed by other stiffening systems. For what its worth, I have read a study where a mustang racer stitch welded all the stampings and seams in a fastback and the results was a 65% increase in torsional rigidity over the stock uni-body. There is no reason to think similar results couldn't be achieved in a mopar by doing the same thing.