While your engineering conservatism should be applauded, let me recommend some economic conservatism instead. Run the stock wastegate on that junkyard turbo (use a bike pump and a boost gauge to check the wastegate opening pressure first), and spend a few bucks on old-school rough tuning.
Sure, a professionally re-mapped ECU or well-tuned standalone would be ideal, but at this low boost, a little more fuel and a little less ignition advance should get you close enough.
Your car is old enough to have a return line and a fuel pressure regulator on the fuel rail. By adding a second, rising-rate regulator on the return line (sometimes called an FMU, or Fuel Management Unit), you can make the fuel pressure increase more quickly when you come up on boost, enriching the air/fuel ratio right when you need it. You can take this step for between $175 for a Vortech FMU to around $250 for a BEGI unit.
Next, you'll want a new set of spark plugs that are one heat range colder ($12), and you'll want to retard the timing a bit. You can dial in the fuel pressure by reading the plugs (free) and get the timing dialed in by carefully listening for detonation while test driving next to a concrete wall that will reflect bad sounds back to your free ears. Given the age of your car and the extra work required to pump fuel to a higher pressure, you might also want to drop in a fresh high-flow pump ($100).
Q. There, that was just under $300 and your car is faster than it would have been at 4psi. When you do finally feel the need to turn up the boost, you should be able to build a mechanical boost controller for about $11.
Mentioning the Dave Point Guarantees We'll Print Your Letter I have a 2004 RSX Type-S with the A-Spec suspension package and Progress anti-roll bars front and rear (non-adjustable). I recently switched from 17x7 HFP Civic Si wheels (previous-generation five-spoke design) with 215/45 Yokohama AVS ES100 tires, to a set of 17x7 Enkei J10s with General Exclaim UHPs, also sized 215/45. When I made this switch, my steering response took a turn for the worse. It went numb on me.
I suspect it has more to do with the tires than anything, and I've played around with tire pressures quite a bit, but it doesn't seem to be helping. The new wheel and tire package is a few pounds lighter than the previous one, so the only other factor I can think of that might have something to do with this is wheel offset. On the HFP wheels, it was +45mm; on the Enkei wheels, it's +38mm.
So if all other factors were equal (wheel size and weight, tire make, model and size, air pressure, alignment settings, etc.) would a change in offset from +45mm down to +38mm have an adverse effect on steering response? And does this have anything to do with the Dave Point?
I'm hoping the right set of tires (and maybe some more aggressive alignment settings) will fix everything, but if the wheel offset may be partially to blame, then I want to address that as well.Scott DrawsScrub, Georgia
A Unfortunately, I've never driven on a General Exclaim, but just from looking, it's likely part of the problem. The Exclaim has an unusual mix of a UHP (Ultra-High Performance) tread compound with an M+S (Mud and Snow) rated tread pattern. The M+S pattern means deep tread, small tread blocks, and lots of void area between the blocks, all of which usually add up to soggy steering response.
When you turn the wheel, the tread blocks squirm first, the carcass flexes, then the car finally starts to turn. Increasing tire pressure will reduce carcass flex, but you can't do anything about tread squirm.