^^^ Don't start scaring people over nothing. I think it's safe to assume that 8-9 out of 10 people on this site with '06/'07 WRX's are running full exhausts, fully catless, and 98% of them don't have boost spike issues. And even if you do hit boost spike... whoopdy doo... no big deal. Just reflash or disconnect the battery and the cel is gone.
I've been stange 2 (full catless exhaust, tune) for 75k miles on my '06 and I've only hit boost spike twice and that was because I was running open downpipe and floored it in 4th gear. I went back to a standard 3" downpipe and haven't had it since.
I personally know of 6 of my friends with '06's and '07's that has stock turbos with full exhausts and not one of them has ever complained of boost spike. It's not a serious issue that people should be scared out of buying exhaust. More important than boost spike is getting engine management. You want to have some sort of enegine management (COBB AccessPort, Ecutek, professional tune, etc) when you install an exhaust.