Upping the IBU ante?

My imperial IPA has been in the primary for 4 Days now and it is still fermenting well. I had an og of 1.077, and used a strong yeast starter.
This is only my second batch of beer and i just calculated the ibus to around 86.
I used northern brewer hops for bittering and cascade for aroma. My goal would be a beer like dfh 90 min ipa. I want to dry hop, how do i figure ibu's after dry hopping?

Also what hop pellet would compliment the aroma and bittering hops I used?

Thanks, homies.

Dry hopping doesn't affect the IBU's so no worries there. If you've already got cascade in with an aroma addition you might want to continue the theme and dry hop with it as well. If you wanted something different I believe Amarillo is a good substitute/compliment to cascade.

With a bu/gu fo 1.12, that beer is going to be a bruiser. I agree that Amarillo is a good choice. That hop is commonly used as a substitute for cascade.

I dry hopped my recent IPA with Cascade. Turned out great.

Amarillo, Perl, more NB, Mt. Hood. Nuggett isn't used for dry hopping much, but the herbal tones can work well with the citrus in Cascades.