Re: Can you please offer some advice on what parts I will need to clean up my install?
The Orion (own 3 225s a 250 and a 2100, personally) and the PPI have built in fuses. Since you have a 4ga coming from the battery and it is fused appropriately, you don't have to worry about fusing the 4ga coming from the distro. However, you do need to fuse the 8ga because you are stepping down the wire size. Something like 2 of the SBF1MAX MAXI fuse holders would work well since you have already ordered the distro blocks.
Also, as I said I own several of the 225s and I am well aware of the ammount of current that they can draw (try feeding a 250HCCA bridged to 1 ohm or a 2100 bridged to 2!). That amp doesn't actually draw that much current. I would be more suspect of the 400X, actually. Either way I honestly think that you should either upgrade to 1/0 from the front of the car or (since you already have distro blocks on order that can support it) add a second run of 4ga from the front of the car. I would also suggest running your ground back to the battery. Dimming is caused by a voltage drop resulting from exceeding the current capacity of the alternator. Power loss from using too small a power wire or having inadequate grounds will cause the amp to draw even more current than normal in an attempt to keep its power supply rail voltage at its normal level. This excessive current can easily exceed the capacity of the alternator, especially with the headlights and other high drain items turned on. Upgrading the "big 3" and making sure that you minimize losses in the power and ground runs are the first step in minimizing and/or eliminating dimming.
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