Recently put the PS LT's on my NNBS and about a week after, it started this. After sitting for any length of time over 15 seconds, it cranks for at least 4-5 seconds before finally firing. It was running pig rich with the headers and I changed plugs and have been retuned to no avail. I checked my coolant temp sensor and it is fine. Anyone have this issue with a NNBS?

 

throwing any codes?

 

I put my long tubes on and ran it for nearly a month before I could get it tunned and I had no issues like this. I hope you get it fixed.