Well, I'm posting this under Intermediate because I meet the criteria, but barely. 
I'm getting prepped to brew my 2nd batch of SNPA Clone, and want to up the IBU's slightly as well as the hop aroma. My last batch was pretty mild to my taste, but I liked the beer in general. Original IBUs were  32.7. So my questions are:
1. Is going from an IBU of 32.7 to 37.1 a big jump, a baby step, or a Goldilocks just right?
2. My 1st batch had 32.7 grams of 7.8% AA Cascade hops added at 5 minutes and 32.7 grams of 7.8% AA Cascade added at 0 minutes. I chill using an immersion coil for about 30 minutes to get to temperature. The hops are in hop sacks which I pull before transferring the wort to the fermentor.  Cascade hop pellets from my LHBS are currently 6.8% AA. I'm wanting more hop aroma, so I'm thinking of eliminating the 5 minute hops and increasing the total aroma hops (equivalent at 6.8%) from 65.4 grams to 90 grams. So will this make a moderate or significant difference? I know this is probably a subjective question, but I'd appreciate feedback based on way more experience than I have. 
I changed the IBU field to reflect my desired IBUs of 37.1 before changing out the aroma hops to 0 minutes, so the Nugget and Perle hops are contributing all the IBUs (correct?). Settling on 37.1 seemed reasonable. Brewers Friend has APAs running from 30-45 IBUs, so I'm somewhere in the middle. 
I've attached the Biabicus with the modified hop bill.
So what do you think? I'm not looking for anything definitive here. Just asking if this is overkill, underkill, or generally the right direction.

http://www.sierranevada.com/beer/year-round/pale-ale

A 13.1 °P equates to a 1.053 OG, so your 1.058 OG at 37.1 IBU would be low.  Watch the bitterness to gravity ratio when you make changes.  The BIABacus will display a .717 ratio when at 1.053 OG and 38 IBU.

Be sure to remove the VAW setting you have in Section D and then enter 38 for the IBU.

If you want a stronger beer, just increase the IBU until you reach a .717 bitterness to gravity ratio
MS

Thank you MS, I'll make those adjustments.

Great question Streamer

This is a question that has a heap of grey areas in it; it's a question where numbers can only be a guide. For example, MS mentioned bitterness to gravity ratio above. It's a term often used, and, we would naturally think it is a term that can be trusted, but, it can't be.

Where Numbers Don't Add Up

Let's say I have a beer with an Original Gravity of 1.050. (We'll assume your hydrometer and measurement technique are faultless  ). The only thing left is to measure your bitterness (IBU's). There are three basic ways of measuring bitterness; laboratory-tested, perceived IBU's and mathematically-estimated IBU's.

The best a home-brewer can do is use mathematically-estimated IBU's, and, if you're not bewildered already, put your seat-belt on, because there are quite a few different methods of mathematically estimating IBU's. There are three main ones though; Garetz, Rager and Tinseth. Of course, we would expect a little bit of variation on what those formulas yield. Fair enough?

Let's have a look though. We'll use BeerSmith2... Here, you can clearly see a massive problem. No need to look further than the first recipe, the first formula estimates about 12 IBU's whereas the third estimates over 28 IBU's.

This is the perfect example of where numbers, and forums, and books, and podcasts, that rely on such formulas, can lead us all astray. (The problem is actually much bigger that what I have mentioned above as most software don't even apply the formulas correctly!)

Let's Get Back to Your Question

A few things... I'd like to see a BIABacus of your original brew and a file of the one you propose (already attached) as when you start changing times, things get messy .

If I am reading things correctly though, your proposed changes will be barely noticeable - definitely not a huge change.

I think this is the intermediate stuff (probably actually quite advanced stuff), trying to identify what it is you want more or less of.

I think, you may not need more hops but, instead, a different hop variety?

And that's where we move from numbers into art I suppose? 

Thanks for the informative answer PistolPatch. Looks like I need to keep messing with this for a while to come up with the flavor profile I'm looking for. I've attached the Biabacus of my first effort with this recipe.  I would like to get this beer to a little more hop flavor and a little more bitterness - closer to the Sierra Nevada Pale Ale, which to my taste is a very balanced beer. I'm not looking for an IPA with this. Making the adjustments suggested by MS did increase my hop bill by a skosh over an ounce overall. 

Thanks for looking.

Sorry for the slow reply mate

Love the balanced beer comment! Yesterday, finally had some time to head to the home brew shop and grab some FWK's (fresh wort kits). On the way back we (Sarah was with me) stopped atour favourite bottle shop.

Fantastic owners, staff, beer range and customers. In fact, a majority of customers are home or commercial craft brewers. Ended up bumping into one of the smaller local commercial craft brewers. He just brewed at home (still does), went all-grain about 4 years ago (full-volume) and now his beers are in the shops here!

Anyway, his beers are balanced!!!! I said to him that I think we have had a run of unbalanced beers for quite a while - a great conversation. And, a great break - there's been a lot on lately.

[center]Down to Busines [/center]

I have your files up side by side in front of me (multiple screens are the best!) A few things...

Section C: No need to put OG on the left and right. You only fill in the right if you want to 'strengthen' or 'weaken' the recipe you are working from.

Section H: Your fermentation temp (and yeast) differs. Nothing wrong with that, just want to know if there is a motive for it. Also, 7 days, I think is a bit short but that's an area I'd love to do some side-by-sides on.

[center]The Hop Bill[/center]

The bit you're interested in

Bear in mind that I am not skilled in this area. Some questions/observations I do have though are:

1. I wonder why Perle is being used? (Working on memory alone, without Googling (short on time), Perle is something I would normally only use in a lager. Check that as I could be totally wrong there.

2. Definitely can't see any probs with your change (the addition of the dry hops). The question is, when and how will you add them, especially given only 7 days fermentation?

...

One Other Thought...

Knowing just how fresh and well stored your hops were before you bought them is often an unknown. So, is it the recipe causing the problem or the freshness of the ingredients?

In my conversation yesterday with the "balanced brewer" I mentioned above, Amarillo hops came up, he had used it in the beer I was sampling. He said it was one of his favourite hops. It was also one of mine, however, I have not been able to brew a great amarillo beer for ages (bought too much of maybe a bad year). We were interrupted then so I never got to pursue that line but it makes me wonder if maybe I should source from somewhere else?

And, just one two more things...

New varieties of hops can sometimes be fantastic in their first five years but then, change completely in characteristics. I'd never heard of that until a few years ago. It's worth bearing in mind though that a recipe that contains some "fantastic" new variety may give a totally different beer in five years time.

The hops you are using are "stable" however...

There are still variations in flavours on stable hops from year to year.

Oops! Better get out of here before I think of 'one more thing'
PP

I just want to add that Perle hops are listed as bittering hops for that pale ale on the Sierra Nevada website. What is the source of your clone recipe calling for Perle hops for a 10 minute boil? That doesn't seem long enough to me.

Good catch on that MS! Interesting.

Perle and Magnum are both great hops. Very clean and nice flavors, classic bittering hops for lagers, and will work well bittering ales. Normally think more bittering for Perle but might work at the 10 minute mark... It has a nice fragrance, at least to me.

For APA though (American Pale Ale), definitely agree with what I think PP was saying... GOT to have citrus flavor Hop for the finishing hops. Cascade is a classic and the one I normally use. Also Centennial...and some of the others. Start mixing other flavors, and there are those now that do, may make a fine pale ale but not so much an American Pale Ale if not a healthy dose of citrus style Hop at the end. You have some at the end in this recipe...and maybe it is enough.

I've never used Perle for anything but bittering a few times, but I like it. If you decide to use it at 10 minutes, for sure let us know how it works...

Wow, great replies!

Pistol, your comment re fermentation temperature in section H. My cellar has an area that stays steady at 63-64F. I understand the US 05 yeast has a temperature range of 58-75F, is this what you are referring to? Am I fermenting too cool? I just looked up US 05 on the Fermentis web site and see that their recommended range is 64-82F, so my first understanding is wrong.

Regarding fermenting for 7 days, I leave it in the fermenter until the FG stabilizes ( don't want no stinkin bottle bombs ), so I've just assumed the 7 day figure was a general guideline.

I pulled this recipe from the BIAB recipes section of this website. The Perle addition at 10 minutes was there already. Should I move it to 30 minutes just to experiment for the next batch? Changing the Perle addition to 30 minutes reduces the amount by about 1/2 oz. to attain the IBUs of 37.1 in section D.

Hi Streamer,

I would give it a shot without adjusting the Perle addition... My opinion. Give it a shot. I think you will be okay. And let me know how you like Perle at 10 minutes...

Wyeast 1056 American Ale Yeast says 60 to 72 deg F. I would think 63-64 deg F should be okay but on the lower side. WLP001 and US-05 are supposed to be the same but list slightly different numbers for most everything.

7 days to ferment an Ale seems like it's on the low side. Might be done but may not. I leave ales normally to about 1.5 to 2 weeks to be certain they are done. Maybe that's just me... Sometimes the Yeast will attenuate more if you let it. But if you bottle it then because you've reached your target OG - and it attenuated more in the bottle - you get excess foam or a bottle bomb I think. (Haven't bottles for years but son had a bottle bomb in closet that took out all but one bottle of a case of beer along with my glass fermenter... )