2010 whippled gt

I have a 2010 gt with a 400hp whipple kit. I bought it with the kit installed i believe it has 32lb injectors as well. Im looking to upgrade the pulley from a 4” to either a 3.375-3.25” pulley. I wanted to know if i would need to get a base/dyno tune done by someone or if i could just use say an x4 tuner from american muscle and do it myself. Also if i would need anything other than a tune! Thanks
 
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