Question about damage stacking with customized weapons

Will a damage increase on a weapon stack with the customized increase? For example I have a 14>50 weapon in the skin I have really been looking for so I am thinking of customizing it for my use. So will a 20% damage increase from customization add to the 14%, or will it just be flat out the customized damage?

Also, can you still mod customized weapons(never tried it)?

ty

Yes, they are cumulative, and yes you can mod customized weapons.

thanks, now i have to decide whether to go ahead and customize the 14>50, or try to get a 15>50( so basically thats a decision between spending alot more for bragging rights, not sure if thats worth it)