I've read a ton of forums on here that suggest using sour cream along with a box mix and a package of pudding to keep the moisture in. My question is, I love using duncan hines, the taste to me in incomparable, but I need to make a denser cake for a topsy turvy cake. the recipe I found here calls for 1 box of cake mix, 4 eggs, 1 cup of sour cream, 1/2 cup of water, 1/2 cup oil, and 1 box of pudding. The duncan hines classic white recipe calls for eggs whites and not whole eggs, which route should I go? whole or egg whites? Would it make much of a difference???

I "doctor" my Duncan Hines mixes ALL the time.  I use whole eggs, not just the egg whites, because I think it tastes better.  Here are my 3 most used recipes.  Each of these recipes can easily be doubled or tripled.

Sour Cream White Cake

Single Recipe:

1 package Duncan Hines white cake mix (16.5 oz.)*

1/2 cup flour

1/8 cup sugar

1/2 teaspoon baking powder
1 cup sour cream
1/2 cup canola oil
3 large eggs
1 teaspoon pure almond (you can also use vanilla, lemon, etc.) extract

* Do NOT substitute any other cake mix, it won't be as good

This recipe is very dependable, consistent, tasty, & durable enough to stack and carve. It also makes lovely cupcakes. You can use gel colors to color the batter of the white cake. This is a version of a cake recipe from the book: The Cake Mix Doctor, by Anne Byrn, ISBN: 0761117199. (Updated to reflect additions required with new, smaller mixes as of 2012)

Doctored Red Velvet

Single Recipe:

1 Duncan Hines Red Velvet Cake Mix (16.5 oz)
1 box white chocolate instant pudding mix

1/2 cup flour

1/8 cup sugar

1/2 teaspoon baking powder
4 eggs
1/2 cup sour cream
1/2 cup buttermilk [or 2 TBSP buttermilk dry mix & 1/2 cup water]
1/3 cup vegetable oil
1 teaspoon vanilla extract

Use flower nails in large pans. VERY thick batter. When a pan is filled ¾ full, it will rise 3/4” to 1” above pan when baking. When cool it will sink to be a full 2” in cooled cake height. Cakes will have some shrinking around outer edges.

SOUR CREAM CHOCOLATE CAKE

Single recipe:

1 Devil's Food Cake Mix (15.5-16.5 oz.)

1 box (3.4 oz) Chocolate Instant Pudding

1/2 cup flour

1/4 cup sugar

1/2 teaspoon baking powder

4 large eggs

1 cup sour cream

1/2 cup warm water

1/2 cup canola oil

This batter has a lot of rise during baking, and will then shrink lower when cooling.  It is very important to use Bake Even Strips and flower nails on pans 8" or larger.

DO NOT OVERFILL CUPCAKE LINER!! 1/2 WAY ONLY!

Fill pan ½ to 2/3 full, will rise above pan during baking, then sink back to 2” cooled height.

Do you recommend using the bake even strips on all of these recipes or just the chocolate cake? what is the flower nail for? 

Here's a thread with lots of photos to fully explain the use of flower nails and Wilton Bake Even Strips.

http://www.wilton.com/forums/messageview.cfm?catid=8&threadid=148262&FTVAR_MSGDBTABLE=  

I also "collar" my 2" high cake pans with parchment paper when I use the sour cream chocolate and red velvet recipes above.  Here's the tutorial with photos on how to collar:

http://www.wilton.com/forums/messageview.cfm?catid=8&threadid=154355  

To answer your question above, Yes, I do use the Bake Even Strips on all cakes over 6".  The use of the Bake Even strips allows the inside of the cake to heat up and "bake" at nearly the same rate as the outside of the batter which is next to the metal wall of the pan.   This practically eliminates the dome and "crusty" over-baked edges that are lower than the middle of the cake. 

The sour cream white cake is not as finicky as the other two and doesn't have the huge amount of rise they do, but I still use the strips and flower nail. 

Flower nail --  http://www.wilton.com/store/site/product.cfm?id=3E30DA56-475A-BAC0-5A840AE69870C73D&killnav=1  

Bake Even Strips --  http://www.wilton.com/store/site/product.cfm?id=AF503936-D3CE-D396-A349624E46D39F65&killnav=1 

(The strips also come in a pack of 2 only for smaller cakes)

Help I tried the sour cream red velvet and it came out dry.  I tripled it as I was putting in 14 inch pan. I want it dense but moist it was dry.  It cooked about 60 min 325.  Please help as I am doing a wedding on Saturday!!  

I also wanted to add I used the strips and the 3 heat nails toward the center.  I am getting panicky as I have to do a cake for 200 and nothing I have tried is working. I have a gas oven.

No idea why yours was dry.  All I can suggest is to use simple syrup.

http://makemessy.com/simple-syrup-for-cakes/

Is there any chance that you over baked it?