I have already done a search and couldn't find anything definate. I want to know what the best line to tap into for the pressure line. I've seen it on the line for the fuel pressure regulator and I'm just wondering if that is the best spot. Also I want to know if anyone can tell me what wire to tap into for the light on the gauge. Thanks

 

It depends on what you want to measure. There's two significantly different spots you can measure then there's all the ones within:

The two major ones:
- Intake pressure after the throttle body: This is how much air your engine is getting. (Measures Engine Performance)
- Intake pressure before the throttle body: This is how much air your turbo is compressing. (Measures Turbo Performance)

The ones within:
- Fuel pressure regulator: This is a measurement of what drives more fuel into the engine. This is the most common spot to tap.
- Blow-off or Diverter Valve actuating line: If you have a combo Boost/Vacuum gauge the vacuum here measures when the BOV works.
- Just before the throttle body: This is where compressor surge first occurs, if it happens.
- Just after the turbo: This is how much the turbo is compressing, and where the wastegate feed is, reflects boost regulation.

In the ones within it doesn't matter unless you have a high resolution gauge and have more than one to compare against. Otherwise they'll look like they all read the same.

The best spot is up to you. I wouldn't think too much about it though, just tap one of the lines coming from the intake manifold.

 

That works, thanks