Individual Throttle-Bodies There are several brands out there and they're all very different from each other. Depending on what you're using your motor for, your requirements can vary. Runner length, throttle diameter, throttle placement and injector placement all play a role in performance. Available kits for the B series include EFI, Fuji Racing, Kinsler, Hayward Performance, Jenvey, OER, SS Work's, Toda Racing and TWM. Bang: estimated +10hp Bucks: $1500+
Turbo If you want a complete turbo kit, check out companies like Drag, Full Race, GReddy, PeakBoost and Rev Hard. Most tuners these days are piecing together their own kit using custom-made manifolds and specific turbos allowing for larger gains. Custom manifolds suppliers include AFI, Full Race, LoveFab and PeakBoost. Turbo manufacturers include Garrett and Turbonetics. Bang: estimated +100hp Bucks: $3000+
Supercharger So you don't like turbo lag but love boost. This is your solution. Complete supercharger kits are available from Jackson Racing and Vortech. Bang: estimated +100hp Bucks: $3000+
Mild Intake We'd recommend skipping the drop-in filter here and jumping to a pipe with a cone filter on it or better yet, a cold-air induction. The D series intake system chokes this motor quite a bit. You'll need to open it up to be able to have a competitive D15 or D16. Bang: estimated +5hp Bucks: $50+
Exhaust For a NA motor, the D series engine should be mated up with nothing smaller than a 2.25" diameter exhaust piping. We'd even suggest a 2.5" (or 60mm) exhaust in case you plan to do any future upgrades. Bang: estimated +7hp Bucks: $350+
Header Stay away from the generic cheap stuff you see on auction sites. They don't fit well, don't last long and don't perform well either. We're not sure why so many D15 and D16 owners swing that way. DC Sports makes a great off-the-shelf header for D owners. But if you've got the money and want a serious header, Bisimoto, Hytech, LoveFab and SMSP offer some of the best units for the D series. Bang: estimated +7hp Bucks: $350+
D Series Medium Throttle-Body A cheap and simple upgrade can be had by swapping out the 56mm throttle-body with a B series 60mm throttle-body. Just make sure to port-match the manifold if necessary. The D, B, F and H throttle-bodies are interchangeable, so if ever necessary you can even fit 74mm aftermarket pieces. Bang: estimated +5hp Bucks: $150+
Intake Manifold Blox, Edelbrock and Skunk2 all make intake manifolds that deliver more air. But if you're on a budget, the D16Y8 ('96-00 Civic EX VTEC) intake manifold is your answer. With its short runners and fat plenum, this is essentially like putting on a Type R intake manifold on a B series, but still not nearly as good as aftermarket units. Bang: estimated +7hp Bucks: $300+
Camshaft and Valvetrain Some of the more popular companies that offer camshafts, valves, valve springs and retainers for the D series include; Bisimoto, Comp Cams, Crane Cams, Exospeed, Skunk2 and Zex. Bang: estimated +10hp Bucks: $300+
ECU If you're not OBD-1, changing to OBD-1 will allow you to use popular systems like Hondata. All you would need is an ECU jumper, an OBD-1 ECU and possibly a OBD-1 distributor. There just aren't as many tuning devices for the non-OBD and OBD-2 D engines. Bang: estimated +10hp Bucks: $400+
Wild Pistons Forged pistons are the way to go for forced induction. But if you're building a NA motor and have a D16Y8 head, you could buy factory P29 pistons (from a '88-89 Integra D16A1) for a huge jump in compression. Bang: estimated +10hp Bucks: $350+