Is the 3.5L clutch slave cylinder the same as the 3.0L slave cylinder? Or could it be bigger? I am looking for a bigger one to help with a high pressure clutch pressure plate.

The 3.5 does have a different slave cylinder, the bore is actually smaller- 3/4" on the 3.0, and 11/16" on the 3.5. There's something about hydraulic leverage I'm not remembering now, I'm not sure bigger=better. The 3.0 has a 635KG pressure plate, and the 3.5 has 750KG- food for thought!

Here's a good explaination:

http://science.howstuffworks.com/hydraulic1.htm

Thats wierd. My FSMs for 97 through 03 all show master cylinder bores of 5/8" and operating (slave) cylinder bores of 3/4". The 97 thru 01 have 580 kg pressure plates and the 02-03 are 750kg.

Given the same cylinder sizes, the clutch pedal engagement distance has to be longer for the higher clamping force in order to maintain a similar required pedal force. (ie. you cannot get more work out than what you put in) Either that or the throwout bearing moves a shorter distance in the 02/03 to release the pressure plate.