I don’t know yet what the net improvement should be, but my gut feeling is that I think the potential is greater than it really is. If my car was a competitive bracket car or a sub-10-second car, then good double-adjustable shocks like the QA1s would be worth the investment. It all comes down to how much money you’re willing to spend to experiment. For example, QA1 sells single-adjustable shocks for my Chevelle (PN TC1958P front and TC1661P rear) for $139.95 each through Summit Racing. That’s around $560 for a set of four. The double-adjustable versions (make it TCD in the PN) are roughly double the price at $1,159.80 for a set of four. I dug a little deeper and found that these prices are for the nice aluminum shocks, but QA1 also makes a steel body shock called the “R” series that can be revalved if necessary but is not adjustable on the car. This shock is a little less pricey at $99.69, saving about $80.00 on the front shock price. Competition Engineering also makes a relatively inexpensive three-way adjustable shock for most popular muscle cars that comes in around these numbers as well.