Just my 2 cents, nice build by the way, but if you go with a good set of long tubes like Dynatech's, Kook"s or ARH's you will pick up about 20 more h.p. than those you put on.
Your leak issue is not the only problem with them, they just welded up a bunch of tubes and made sure they fit the application, they were not designed or engineered to make power, they are just a low cost alternative. Yes they do increase your power over the stock manifolds, but your leaving power on the table if you dont put the best on. There is a reason why the name brands cost so much more, and thats because of the time spent to ensure they make max power.
Back in '10 I was involved in an independant comparison of long tubes, 1 SS, 11 sets of long tubes, 1 base tune for long tubes. Over the course of 2 days we switched out all 11 sets and dyno tested them. Results were a low of 18 rwhp gain to a high of 44 rwhp gain, the 3 brands I named earlier were in the 40+ rwhp gain, all the others were less. I'm not here to knock any of the other brands so I wont name them, you just stated you had a goal of going 10's and if thats the case you cant leave horsepower on the table.
I've gone 10.80's and it took 713 rwhp, M/T dr's, and a track that was prepped perfectly. I've run on other tracks and had traction issues that have dropped me in the low 11's.
Good luck with your build.
URR2SLO - If you're not going fast enough, get out the way......