B6 1.8t only getting 9 psi max, most gears spikes at 7 and holds 3

[slabdabs]

Hello guys. I've reached a problem that's got me stumped and cannot seem to find an existing simmilar thread that doesn't involve lean mode as an answer. I drive a 2004 a4 1.8t quattro with a six speed. Today I started it up, tad bit Cold out and suspect I also have a new thermostast issue as well with my engine temp running suspicious below operating range despite the spirited/long drive I took this morning. I've noticed a loss in boost that's been inconsistently between 3 and 9 with no turbo whine as if it's blown. No smoke out of the exhaust, other than slightly at startup though I am overdue for an oil change. I've noticed in 6th gear when the car was running good I would get 11 psi and right now in 6th the most ove gotten is 9. Drove 4 times with the same results today. My buddy tried telling me it's due to cold weather, but it was 43 degrees today. I've driven in the high 30s with full psi. When I first started the cat up a second time it got full boost for maybe the first few blocks and then the same, a lower boost range on the rims, And a lower psi. I'm not a very good diagnostic fellow but I am attentive and can answer questions assuming someone asks. Please help me brainstorm this one, I'm terrified of problems I don't understand and this is the first turboed vehicle I've owned. It has only slight mods, intake, 034 motorsport diverter valve, high flow cat and magnaflow catbbsck with high-low res, mufflers and such. I have an acs vent pod to read my boost otherwise my turbos making normal noise and spool soinds and I would have wrote the performance decrease as cold weather as my buddy if I didn't have the pod.