Welcome to the site mate.
First of all, ditch the powerflow. The oem exahaust is actually better than a powerflow mate. A cold air intake with an uprated filter should help a little bit. Get yourself a 4-1 manifold as well mate. This will improve the power higher up the rev range (as this is where any Honda performs best). I would de-cat it as well, but you can get a sports cat instead. Both will do pretty much the same job, it's just that a sports cat helps lower emissions.
Don't overlook the power of shedding weight as well. Carbon bonnets and spoilers are both good for this (they look good as well imo). Spend some money on some decent coilovers as well. It's not just about going in a straight line. The last thing would be to get your alloys wrapped in some god rubber. There's no point having the power if you can't put it down.
Hope this helps.