Courier Mode or Commercial Mode for export shipments?

First time exporter here!

I have taken two quotes from courier companies who have given me two options :-

1. Courier Mode

2. Commercial Mode

Courier mode is cheaper but I will have to undervalue my invoice, whereas Commercial mode will be expensive and will require a lot of documentation. What are the documentation required for Commercial Mode? I have my IEC and will apply for LUT.

And will there be any pitfalls in my accounting by choosing Courier mode by undervaluing the Invoice?

Also what about GST credit? I will be buying raw material by paying GST.

Thanks,

Kunal Vanjare