I've heard great things about Steve too, but re Boostworx - your list is rather large, and its not surprising that they might be wanting to get work out of the way before starting on a bigger job like yours. I would be surprised if anyone said that it was going to only take a day, as quite honestly some diagnostic stuff can take several days, and a full decent tune is not a 5 minute job. I've used Boostworx before and they've always done good work to my car so I've never really been bothered when they said they needed to spend more time on it - after all, a rushed job is no good for the business or the owner... quality work needs quality time. Sure you can take it to some other place and git'r'done on the quick but can you rely on that work? The poor man pays twice.
I know its a damn inconvenience when you dont get your car back on time but better to find a quality workshop that gets it right the first time rather than having to return multiple times. My previous workshop took 3 months to do a head gasket repair and refurbish whence they'd quoted 2 weeks - and at that stage it was 50% and I sent it to boostworx to get completed - incidentally they hadnt even started disassembling it so Ruby came and disassembled it for me, the champ that he is
Its not a case of more interesting work but more a matter of first come first served. Sometimes they just happen to get some difficult jobs that were booked out previously, that just happen to blow out their estimates and thats all there is to it. Shit happens
In either case, I'm still happy to use Boostworx, as I'm happy to use Wilall. Manta are 101% quality from what I've heard and I'm sure you'll be satisfied with his work.
-D