whats up, i just bought a 2001 Sierra w/ a 5.3...its a reg cab, step side. I got a 40 series flowmaster single in dual out put on it last week and i bought a AEM intake today off the internet. besides that its bone stock, what should i get next? also i was wondering whats the best way to start off the line with an automatic transmission? leave it in D the whole way or 3? or start at 1 and shift up? thanks for the help.