I'm driving a swift sport zc31 manual. My clutch slip when I accelerate over 3k rpm. The acceleration comes in after a delay of about 2sec. When I floor, the Rpm will rise like it's in neutral gear and then will go down and accelerate the speed. I just changed a recon gearbox and new clutch kit 2 mths ago. Went back to the workshop and they told me it's normal cuz I changed a normal clutch, if I change a racing clutch then won't have this problem. Anyone can help on this?