What To Replace While Engine/Trans Out

[996tt2002]

Planning on having the IMS changed on a 98 Boxster with tiptronic, 26kmiles. Have been told that engine/trans have to come out to do so. Figured I'd change these parts at the same time:

underdrive pulley for ps
water pump
low temp thermostat
AO separator
spark plugs/tubes
after market exhaust

Any suggestions as to what else may be good to change out at this time?

Thanks, Rob C.