Imperial (Double) IPA

I am boling an IIPA tonight. It's a Midwest extract kit with speciality grains (Kit 265W w/American Ale Wyeast 1056). It is all hop hop hop... Recipe requires;
1 oz Chinook 60 min
1/2 oz Cascade 45 min
1/2 oz Centennial 30 min
1/2 oz Cascade 20 min
1/2 oz Centennial 10 min
1/2 oz Crystal 5 min
2 oz dry Cascade after one week fermentation.

I start with full 5 gallon to boil and add up another gallon or two to maintain full 5 gallon before the last fifteen minutes of the boil. My reasoning is that I get more flavor diffusing from the hops (higher volume -> less concentrated -> more diffusion).
Is it okay to change the times to get a personalized flavor and aroma? How would you play with it based on your tastes and preferences?

 

I would simulate some first wort hopping by steeping your 60minute hops the water at 170F for about 10-20minutes before bringing it up to the full-on boil. But right now I'm all about FWH and have yet to try it.