Can I upgrade to 5.1?

I know you guys are sick of these questions but I searched and just want to double check:

I have:

iphone 4 GSM
baseband 4.10.01
Currently running 4.3.3

I've preserved the baseband and looking to upgrade to 5.1. The only issue I have is that I have not saved my shsh blobs from what I understand I can no longer do it.

Can I upgrade to 5.1 without saving SHSH blobs? Thank you.

EDIT - Also I am not looking to jailbreak.

 

What! So you're saying that upgrading my phone is no longer possible? I thought someone could upgrade their phone preserving baseband without saving shsh blobs. Of course running the risk of if they ever wanted to downgrade they couldn't.

Are you saying that it is impossible for me to upgrade to 5.1 altogether?

 

Okay, I think you guys just saved me from making a HUGE mistake. I didn't want to go into the details, but here is what I've done so far:

I've preserved my baseband using snowbreeze and was following the directions here:

http://www.ihelplounge.com/ihelplou...4-to-ios-5-while-preserving-the-baseband.html

Once I got to the restoring iTunes part, I realized that I do not have the SHSH blobs saved and that it is impossible. From what I understand, SHSH blobs are only necessary if someone wants to downgrade their firmware to a previous one that they have. I have no intentions of downgrading, unless of course something happens that requires me to do so.

So if I were to go and upgrade to the latest firmware with using the method above in preserving my baseband, will it be ineffective and I can no longer use my unlock? The way I have my phone unlocked now by the way is through using a gevey sim tray.

EDIT - Or are you saying once I Shift+restore on iTunes it would have simply not worked?