Drive Axle and Head Gasket Replacements

[iaincamp]

My 2001 Boxster S (30K miles) has some needs and I'd appreciate hearing from those with experience.

Left Rear Drive Axle: I had the right rear drive axle replaced last year, as the rubber boot had torn and allowed dirt in, and it was cheaper to replace it than rebuild. I didn't realize until recently, that the PCA-recommended mechanic had used a non-Porsche replacement ($300 vs $800) but its been fine. Now the left one needs to be replaced. I'll need a "Special Tool 9560 (ball joint press)" which is new to me. Has anyone here with modest skills done a successful replacement? Any thoughts on the non-stock part?

Valve Cover Gaskets: While I have the car up, and apart, I'm planning to replace the valve cover gaskets. Do I need more than the parts and the Bentley manual? Anyone here try this and wish they hadn't?

Exhaust: I have to remove my stock exhaust system to do this work above. I'd like to hear back from someone who has installed a Borla Cat Back exhaust.