ABS engaging during hard braking

[shlim8]

Interesting topic... I think I have the reverse of the TS....

At high speeds if I brake hard, on my front brakes, the abs actually sometimes allows the tires to skid (???!!!) slightly, usually just one sound then no skidding but no abs as well. If I step any harder, the ABS will kick in. The skid usually last a split second to at most a second.

I've changed abs sensors on all 4 brakes and even changed the front brakes to the S brakes, but it still behaves the same.

It's as though I've got "lazy" abs that is pretty slow in engaging.

My mechanic says its normal as "Porsche determined this way you get the most effective braking". Don't know whether to believe him or not ?? I've never had a car with abs that allowed any skidding !

My front tires are PS3 and the rears are N specs PS2, if that makes a difference.

Any thoughts ? I hope it's not the abs unit... those things are expensive !