3gs on 3.1.3 upgrade to 4.1 question

[Roco2]

I tried to read to stay clear about this theme, im still confuse. There are many model / boot / baseband conbinations so this is my phone
Iphone 3gs on Ios 3.1.3 jb with spirit an unlocked so far everything its ok.
Base band 5.12.01
Bootloader 6.4
Mc model
I boot 359.3.2
Shsh blobs on 4.0. 4.01 and 4.1

Want to upgrade to 4.1 but dont want to have issues with base band and new/ old bootroom
Is anythig i should know before use pwnagetool an make the upgrade to 4.1 and unlock.?

Thanks in advance

[dotFIVE]

Download your SHSHs via TinyUmbrella just in case.

You should be good to go man. Just make sure iTunes is updated to the latest version. Download stock 4.1 firmware. Open up Pwnagetool 4.1; cook up a custom 4.1 firmware; after firmware is cooked, follow directions to put phone into DFU mode; alt + click on restore; choose the custom 4.1 firmware; restore; rejoice; send me your money (optional).

Since it's custom firmware, your baseband will not be updated and you will be able to keep your unlock. I was in a similar boat as you yesterday but I updated to custom 4.1 just fine.

[Roco2]

That is great men.!
Thanks for you time and your knoledge, about the money thanks god its optional
Excuse my bad english.
See you around

[eyeRobot]

Let us know how you get on Roco.

For info, not particularly relevant, there's not much point saving your SHSH before doing the restore, as exactly the same ones will be available after the restore. You can only save 4.1 SHSH at present and if your other ones are already on the cydia server now they will still be there after restore. In other words, even though you're on 3.1.3 you can't save SHSH for 3.1.3 as apple aren't signing it anymore.

[Roco2]

I been busy for a long time, but today have enough time to do de upgrade thing......
Everything works just fine
Upgrade ok
Unlock ok
Pd i use pwnage tool 4.1.2 works ok

Thanks again for your help.

[eyeRobot]

Now backup your SHSH if you haven't already!

[iats7]

Please answer me before I mess my iphone: I got an iphone 3gs firmware 3.13 and there was no shsh(tinyUmbrella told me I'm too late for that). Now can I still download a costumed firmware 4.1 and upgrade?? What I was reading would be: running TSS and shift+restore to my saved costumed firmware???
Thanks

[eyeRobot]

You don't need to use TSS server with custom firmware. You should just hang on for a few days and some new tools will come out to jailbreak and unlock 4.2