I have installed a couple of the MBRP setups and they usually go together pretty well for me. Making sure you have full engagement at each joint is key. Also depending on the size of the leak, if its really small it will carbon up quickly and basically seal itself, one small advantage of DI engines... Other than that, thats why I say I usually spend more time making sure the fitment(including checking leaks) is to my liking than I actually do removing the old one and putting the new one in the car.
2011 F150 FX4 Blue Flame Metallic SuperCREW EcoBoost 371RWHP/458RWTQ
97 Cobra Coyote Swap in progress
2013 Focus ST3 Performance Blue-Gone
89 Mustang 5.0 Turbo 670 rwhp-Gone
03 SVT Focus Turbo 326whp/278wtq-Gone