With MHD you should be able to just buy the “flasher” license. This lets you customize cold start delete and other options on a stock power tune (I’m like 99% sure) their support is good and will get back to you quickly if you want to 100% confirm. Adding link to the flasher license n55 info.
https://mhdtuning.com/products/mhd-f...icense-for-n55
I have MHD stage 2+ current and have turned off cold start. Its great.
In the interim, if you want to be really cost effective, you can actually just lightly press on the gas for maybe 20-30 seconds immediately after startup and it will stop the cold start noise. I was doing this effectively prior to flashing a tune and it worked like a charm.