Well, it always felt like that with the oem clutch and flywheel. Let's hypothetically say that I rev the engine between 2,000 - 3,000 rpms, and come completely off of the clutch. What happens next is the clutch will make a noise similar to a straight cut gear transmission slowing down rapidly, followed by the smell of burnt clutch.
When I got my UUC lightweight flywheel and clutch combo the problem was even more apparent, but worse. During normal driving and normal engagement the clutch always felt like it was slipping. So I took it to an Indy mechanic three days after the install, and he said that my clutch is worn out and needs to be replace. I told him it must be something else because the clutch is brand new. A friend told me to get a Stainless Steel clutch line, which I did and it helped dramatically. Now, it engages just like and still gives me the same original issues that the oem clutch and flywheel did.
One last example is: If I'm on an incline hill and give it a little more gas than normal (not much just a 2-300 more rpms) then the clutch feels like it is slipping and makes the noise I mentioned previously.
UUC Lightweight Flywheel, UUC SSK & DSSR, UUC Anti-Swaybars, and Supersport Coilovers + ME = Fun FTMFW!!!
Euro-Spec front and rear M3 bumpers