Bear Republic Racer 5

So I came up with my own Racer 5 clone recipe based on another clone recipe I found as well as the specifics listed on Bear Republic's web site. I brewed it last weekend and it's just about dry hopping time. For those of you that have had it, how many ounces should I dry hop with? Right now I'm just doing 1 oz, but I'm thinking maybe I should bump it up?

12 lb 2-row
1 lb Cara-vienna 20L
1 lb Wheat Malt
.5 Cara-pils/Dextrine

1.25 oz Columbus @ 60 min
1.00 oz Cascade @ 15 min
1.00 oz Columbus @ 5 min
1.00 oz Columbus @ Flameout
1.00 oz Columbus Dry Hop

WLP051

OG: 1.071
SRM: 6.3
IBU: 70.2

For Racer 5, I would dry hop with .25 Centennials, .25 Amarillos, .25 Cascades and .25 Tomahawk.

I drank one of these the other night and thought the grapefruit taste came through strongly. I would agree that dry hopping of centennial and other is necessary for this taste.

I'd bump the hops a bit more - I actually just opened a racer 5 clone that I did and it's great, but I wish I'd added more dry hops. I suppose I still could, but the keg probably won't last long enough for them to really take effect.