HELP! I want to update from Custom 4.2.1 to 4.3.3.... How?

[karloz25]

I have a iPhone 3GS 8GB with 4.2.1 CUSTOM FW *Tethered JB*
I want to UPDATE to untethered JB 4.3.3

My question is how?

Do I update to Official 4.3.3 first?
Or go from Custom FW to another 4.3.3 Custom FW?

My Baseband is 05.15.04

Thanks!

Do I go into PWN DFU?

Give advise the proper steps...

[iYeow]

The current firmware is 4.3.5, you need 4.3.3 blob for restore.

[karloz25]

Im new to blobs...

Let say I want to update in the future to any FW, 4.3.5 or even new soon to be released 5.0 FW, since I am already JB'n can I simply use itunes shift restore? or is there something special i need to do before attempting to update?