This is hot off the press..

I have a 2001 TT I bought 7 months ago.

Now mods are Apr chip which I put on. and mod shack boost machine. Turned up to 4.5 turns boostin around 23 psi. I fugured that wasn't too crazy from what I read.

Now for the codes.

P1555
P1340
P0343
P1602

Some please tell me what they mean.

And for the smoking gun..

Compression test now this is what they are telling me.

cyc -1 15 PSI
cyc -2 30 PSI
cyc -3 0 PSI
cyc -4 0 PSI

I know they all should be around 150 -180 PSI

Now this is what the shop is telling me and they are not known to be a good shop.
they said the top end is gone from the codes...
What do you all think?

2001 225 TT blue on blue W/Fat 5's
Stock for the time being.

2000 S4 Silver