I assume you have a transbrake. What rpm are you launching at? You say no tire spin. That may be one of your problems. Dead hooked on a slick leaves you “stuck” with your hard ratios. Induce some spin to get your engine in a higher rpm range. Effectively this will change the ratio the engine “feels”.
My opinion would be to raise launch rpm and stiffen the shocks. Maybe change the caltrac bar angle to induce some spin.