Ive got a 03' DE with stillen true duals and im adding stillen headers and stillen cats, Running 5/16ths spacer-injen/RC2 filter and im going with UTEC for the my tune,
first - What spark plugs should i change to balance 250 and up hp?
Is Utec a good option if I go forced induction + a whole new internal build?
What am i missing engine wise to achieve 250 hp? 260?
What pulley kit am I looking at when running 2 JL W6's?
Whats next?

 

well, this isn't an NA build, but to answer your questions

stock plugs are just fine - stop chasing hp #'s, they are all relative to the dyno you use, so they are going to be largely arbitrary. The #'s that matters are the difference between your car stock, and your car completed, on the same dyno.

A UTEC can work fine...again, depends on your future goals. There are tons of threads about the ecu requirements.

For your pulley and 2 w6's, your pulley has no idea that you have subs, that is determined by your amp(s). Post up in the audio section

 

will this help build cred wit yo br0's at yo street races?

 

This guy-

 

High flow cats combined with a decent exhaust, UTEC, and plenum spacer will get you right around 250 whp. So you're not missing anything. Just get a good tune.