Alot of aftermarket intake manifolds actually make you lose power unless tuned with a piggy back or chipped ecu or whatever. If you're running a gsr and the ecu is stock, that is your main problem. There is a set of secondary butterflies inside the stock manifold. I don't know if you noticed, but on alot of dyno plots with the stock gsr manifold being used you see a dramatic drop in horsepower when vtec kicks in. It's only for a few hundred rpms. Then all of a sudden it'll jump way back up there and start making power again. The reason for this is because the secondary butterflies take a second to open up. It's programmed in the ecu to do this, for more midrange power . The skunk2 manifold is a straight runner intake manifold much like the type r manifold. They are setup for top end power. You may want to get a vafc to mess with your crossover points for vtec and change how it engages. You might have to raise your vtec point. You may also want to try a type r ecu. You just gotta watch out because if you have a immobilizer it'll cost like 200 to have it programmed to the ecu. Thats only on newer models like 99 and up I think. My old car stock ran a 15.4. It was a 2000 2dr gsr. Remember the 4dr is heavier. With better tires and an aem intake,dc 4-1 headers, spoon flywheel, and stage 1 exedy clutch it ran a 14.6. I hope I've helped