PETG Curling

I am having some bad luck with PETG. From the reviews I have read it seems to be an awesome filament that I would love to work with. However on anything larger than an inch I am getting curling on the edges. I have tried a few things:

I increased the heat and slowed the first layer down to increase adhesion. I also turned the cooling fan off. I am printing at 249 first layer and 245 2+.
I added 8 brim outlines 10mm from part.
Ive tried modifying the design to add tabs on the edge and tape these tabs down to attempt to hold it down with no luck.
I added a sheet of PEI to print on as the stock bed is not level.

I am using a gmax 1.5xt+ without the heated bed. Is this where I am going totally wrong? Do I need to invest in the heated bed?

Kyle said I can try and super glue the part to the bed after a few layers have been printed, But I am looking for a solution to the problem instead of a band-aid. I really dont want to have to super glue every part down.
did you sand your pei with 1000-1400 grit sandpaper? PEI from the factory is very smooth and one side can be shiny and VERY VERY smooth... Either way, I sand it down every few parts.
Also, the first layer will need to be pretty smooshy... I also use 75 degrees bed temp
I used both sides of the pei with the same issue, however I thought the matte finish side the bottom layer came out better so I have been using the smooth but not as smooth side. I will sand it down now. I do not have a heated bed, and have a feeling that is part of my problem.
Are you using the buildtak surface?
If so, dont :)
Not saying buildtak doesnt have its strengths, but PETG isnt one of them.
For instance I have the bare glass heat bed. and
1. 16x16 glass with PEI
2. one with buildtak (exclusively for ABS , with no curling)
3. one with another substance
4 one with just glass

I switch them out as needed with alligator clips.

With Petg on PEI i have ZERO curling with a fairly smooshed first layer :)
I got it to stick!!!

No i am printing onto PEI. I have the aluminum heated bed, a glass sheet than the PEI. The PEI is attached to the glass to ensure its flat.

Now my problem is keeping this extruder aligned. I get halfway through a print and the extruder starts to click like its misaligned. UGHHH.

Got to love 3d printing as it always gives you a challenge :)
extruder is clicking???? that usually means you are pushing filament too fast for the extruder to keep up. Personally im a little underwhelmed by when it happens on the gmax (and im using a e3d hotend). seems to happen before i reach 120mm/s printing speed, which is still good, but with how rigid this hot end carriage is, i can print faster, and keep quality, its stunning.. maybe ill run a test print at 120mm/s and show it off :)
Stock Hotend yes. Its nearly new, but I will clean that gear up with some alcohol and see if that helps. It doesnt click until into like the 5th hour. shorter prints present zero problems.
very nice... although i think 255 for the stock hotend is really high... Perhaps kyle or gordon can correct me...
Being peek that temp scares me.
My guess is the heating chamber is NOT getting to 245 when you printed it there, because I print at 245 without any clicking at 80mm/s on my e3d... That extruder IMHO is not working right, or the PIDS arent dialed in. but glad its working, just be careful
for the cost, an upgrade to the e3d hotend is a no brainer.. you dont have any concerns with heat creep etc... I can take the nozzle to 285 without any issues, allowing me to print polycarbonate etc.
Just my 2cents.