No idea what their 'formula' is?? - but they're pretty easy and nice and good to work with - I only have 1 medical card with them that I got at my dentists on a whim for some cosmetic DDS work I needed done from a rollover MVA - and my DDS Insurance only pays like $2000 with an insane deductible (everyone knows THAT feeling and story) sigh... But thanks to them - I was able to get all my work done in 1 sitting and they gave me an 18/mo. 0%APR deal to boot!) 
- So I stretched about $5K in DDS work out over about 9-10 months and PIF halfway thru their offer (had no idea they had so many other retail cards!!)
FYI - I need to get an engagement ring here soon too - and whilst I'll pay cash for most of it - she just informed me that she wants a 2 CT(ish) center stone (ouch!) when I already had a sweet 1.45 selected - so I found the best jeweler on Synch's website here in my state and they are a Synchrony merchant and asked the store mgr what was a 'typical' CL for my income and credit/FICO score would be? (it's also nice that they put your Bank 9 FICO score on every statement and can compare that to others that do the same (Wells, Discover, AMEX etc) - It shot up about 20 pts this past month and am getting closer to my goal of 800.
But I digress.... My reason for adding a comment is that I asked them for $4500 when I was at my DDS to pay for that day 20+ months ago with Care Credit and they gave me $6000 right out of the gate - So, that covered the work I needed - but also want to build this line up higher with 2 yrs of perfect payments and a 4 figure initial CL, I think that'll help me when I go to the jewelers? (I only have 1 HP Inq. on TU, and my score is hovering around 775+)
So I just logged on and hit the CLI luv button easy peasy... I found it interesting that they wanted my NET income - not GROSS? - so I did some loose math in my head, and basically knocked 30% off my annual pay (they wanted my monthly too, not annual?) - and even with that reduced income - I asked for $11,500 and they came back approved me instantly for $15,700!?! - Yippee! .... I have to have an implant (DDS) done (possibly two?) so that's gonna cost about $4K x 2 when all is said and done - Sadly no more 0% interest free offers though, as that's now lapsed - I also have over $12K free on my new Discover IT ($0 BAL) with 8 months left on their 0% offer - so could use that - but rather use this card as it's for 'medical' and use Discover for it's perks and bal matching etc., etc. (FWIW - that truly turned out to be a great card to get! I highly recommend Discover for those wanting higher lines and some nice perks.
The $9K Sych boost I just got will drop my UTIL to below 2% now, so that's another benefit of asking for a CLI - but as the OP said, don't overuse it - I waited almost 2 yrs before asking for some luv - and they treated me very nice Thank you Sync Bank! Now, I hope all that love passes on when I go to this high end jewelers - as I have my eye on a Swiss watch that I've been wanting for about, uhmmm, my entire life LOL - So, I figure that can be my 'wedding gift' to myself ) Kidding - Kinda - Maybe? - We'll see!?!... Just know their deals are a helluva allot better than these places offering AFFIRM credit for 12 mo. at 29%APR+ What a ripoff that is... ouch.... Hopefully they'll give me that same 'starter' 0% APR deal when I get a new card ... Great company to do biz with and have nothing but awesome things to say about them - Congrats on your MASSIVE increase ($300 to $4000?!) that's unheard of these days... esp after just 1-2 months? But there's another example why i like working with these guys Cheers - BB
PS: I know there's allot of rambling info here- but I did "break it down" into small tight paragraphs to make it easier to read - but for whatever reason this site always removes my formatting and creates one massive huge note!?!? - So my apologies for that - I'll try a different browser next time - Sorry 
@Anonymous wrote:
PS: I know there's allot of rambling info here- but I did "break it down" into small tight paragraphs to make it easier to read - but for whatever reason this site always removes my formatting and creates one massive huge note!?!? - So my apologies for that - I'll try a different browser next time - Sorry
I don't know why you're unable to add paragraph breaks, but I went back and added some for you to make your post more readable.
Until you can get your browser issue worked out you might want to stick to making a single point per post/message. 
Thanks - I'm assuming you're a Mod to be able to do that? (Duh me! It clearly says "Mod" next to your username) - So I appreciate the help (I too don't know why it strips out the formatting) - That said though, while you were doing that, I saw a typo and a miscalculation on one CLI I got - so at the same time I went back and corrected those 2 items - and it's now back to being one big blob again - I had no idea you were working on it - so, I'm sorry to undo all your hard work there - Obviously it wasn't intentional as I had no idea you were working on it too - Thanks just the same though BB
BB