i had my stillen catback done at golden auto muffler in SF. they got one in daly city also next to ASP. takes about 20 minutes and charged me 100.. when i saw how easy, i coulda done it myself. all i need to do is lose about 60 pounds and be able to squeeze under the car

 

No lights no vdc problems after my exhaust install
Mine done at mod a car ...livermore (no doubt way out of OP's way), around $50-$70 for install. Had them throw it on after my base dyno done.
On lift very easy; on jack stands harder. Me old fat guy preferring the latter now-a-days for DIY

Exhaust shops could do this. Don't need a specialized G or Z shop. It's all pre fabbed...plug and play.
Somewhere there used to be a place that your rent a lift in their stall /hr /day /wk, bring your own tools, etc., but don't think those places around anymore.

Another resource for shops if you rather not DIY or exhaust shops not touch your G:
https://g35driver.com/forums/nor-cal-g/156204-unofficial-bay-area-automotive-shop-directory.html

 

Got my hks installed for $60 at a local muffler shop...Dont know if you wanna drive out to the cuts for the install though....