I suggest that you drive a 2005 Mustang before you make such a drastic change and see if it's really for you.
I have always been into V8 American cars. I have friends that have Porsches & BMWs. One friend has a tricked out 914/6, another has a mid 80s 911 coupe, still another has a late 90s 911 Cararra (956???, I know it's really expensive and has HUGE fender flares) and an aquaintance runs a Porsche restoration shop. I've driven a lot of Porsches and while there are nice cars, awesome in some aspects, they just aren't for me, just plain too small and go-cart like.
While many of my Porsche purest friends love the old 911 and despise the new 911 (sound familiar, like the SN-95 vs S197 arguments here), to me the old 911 is old and crude (like a SN-95 Mustang). IMHO the new 911 is superior in EVERY way to the old 911.
I've had a couple 67 Mustangs and a lot of Fairlanes & Torinos. The 2005 Mustang is exactly what I want which is a car that has styling and attitude just like a '60s muscle car, but with 2005 refinements.
While I know a 2005 Mustang GT is the right car for me, only YOU can answer the question "Is a 2005 Mustang right for you."