Western Digital offer evaluation

Got an offer for Staff engineer, but interviewed for principal engineer position. In bay area.
Base: 140k
Bonus: upto 12% per year
RSU: 26k/(4 years)
Sign on: 15k
TC~ 163k, excluding sign-on

Current TC @ Intel, G6 (non bay area):
130k (base plus bonus plus stocks), around 30k unvested RSU
YOE: 6

Dont have external competing offers right now.
This looks like a lowball.
How to negotiate?
Should I negotiate for principal (they said not enough experience for principal, but got the offer within a day of interview)

Update:
Revised offer was bumped to 145k base (+5K) and 25k sign on (+10K) and same RSU as before and it was the best they could do. I ended up rejecting the offer. Will keep interviewing.
Thanks to everyone for all your inputs! Really appreciate it!

#hardware #semiconductor #offer #westerndigital #intel #micron