1. DME already contains a good amount of carapils, so adding more is unnecessary and not recommended. Depending on the grade of DME, some maltsters even add crystal to their extract.
2. Efficiency in a partial mash or extract beer is usually never as low as 70%. I woudn't worry about adjusting the efficiency factor if you're used a program to create this recipe. An exception would be if your recipe is something like 80% All Grain / 20% Extract.
3. Topping off with plain water is one of the worst things you can do for an IIPA. I strongly urge a) getting a bigger kettle, or b) brewing a smaller batch via a full volume boil with no top off water.
4. FG is a bit high, but not unreasonable. To combat this, substitute 8-10% extract with corn sugar then make a big healthy yeast starter with WLP090, and ensure that the wort is properly aerated before pitching. Regulate the ferm. temp. closely and wait 3-4 weeks before bottling. Follow this advice, and your FG should be a few points lower than 1.018.
5. Don't FWH. I strongly believe this process is very Anti-IIPA. If you want more of a rounded bitterness, then add smaller early and middle charges, and pound it out late in the boil and the dryhop.
6. Bitter with your Columbus. It makes the most sense since it's higher alpha. The rest of the recipe looks good, but I would personally nix the Citra. It will dominate the beer and change it from citrusy more toward tropical fruity. Use Cascade and Columbus instead.
Looking for some feedback on this recipe, a fairly big IPA:
5.5 Gallon batch
3.75g boil
70% efficiency
O.G. 1.073
F.G. 1.018
IBU 67.6
SRM 5.8
6lb extra light DME
3.5lb two row
1lb rye
0.5lb carapils
0.5lb caravienne
1oz Cascade FWH
1oz Columbus 60'
0.5oz Columbus 30'
1oz Citra 15'
1oz Amarillo 10'
1oz Cascade 10'
1oz Citra 0'
1oz Amarillo 0'
1oz Cascade 0'
Dry hop 7 days:
1oz Amarillo
1.5oz Cascade
1.5oz Citra
