Ok my car just started this recently when im driving my car down a street say 30 mph my oil pressure is at 1/4 the way up like 20, and then when i slam down on the gas it gradually goes up to 40, but when im at a stop light it sinks down to 0 or barely above, because even my Check Guage warning light comes on cause its in the Red. What could be causing this. I recently put SLP Loudmouth Cat-Backs I'm wandering if this could of caused it somehow?

Also my Voltometer is reading really high to right next to red in guage. What could be causing this also?

Thanks...

 

when iam idling after my cars been warmed up its around 5-10 oil pressure but if ur like 1/2 or maybe 1 qaurt low on oil that will happen make sure u have 5 qaurts in there check ur dip stick.