I don't claim to be an expert here, but sounds like you've got several things happening at the same time.
First, with 1/2 tank of gas, all that stuff in your trunk, hot weather, and a crappy launch, low 14's are probly about right. Remove the weight, run in cooler weather, and improve your launch, then low to mid 13's are likely.
While a boost leak is possible, it's not likely. If you've got a leak in one of the smaller vacuum/solenoid hoses, the turbos would likely be over-boosting. If you've got a leak in one of the intercooler hoses, BOV, or y-pipe, you'd probably hear it or it would blow off and you'd know it.
The only gaskets at the turbo are between the turbo and the exhaust manifold, and the turbo and the pre-cat. If either of these are leaking, it would be an exhaust leak and not a boost leak. And yes, it IS a real pain to replace the gaskets. The front turbo is not as bad as the rear, but it's still a pain.
If you are leaking oil from the turbo, you could have a problem with a leaking oil seal in the turbo. If this is the case, your intercooler hose would have oil in it also. If not then make sure it's not simply an external leak from the gasket on the oil return line.
If you're seeing smoke coming from the pre-cat under the turbo, and you didn't find any oil in the intercooler hose (see above), this is more likely due to internal engine problems, such as bad valve seals or rings.
Doubt your plugs are the problem, although most people (myself included) recommend staying with the stock NGK plugs and gapping them at .032" -.034" These plugs and gaps are tried and proven.
I didn't see a boost gauge in your list of mods. If you don't have one, you MUST get one to make sure of exactly where you're at.
Sorry for the long reply. Just trying to shed a little light based on my experiences. Hope this helps.