My 3rd gen MODS:
[2] K&N filters for the intake
3" SS downpipe
3" SS midpipe (Airpump removed.)
SS catback Apexi GT exhaust (recently added).
Factory ECU. (yeah i know)

Here's the problem: Recently i changed the plugs and wires. I also just put on the new catback exhaust. Before those 2 things were done, i was getting a boost pattern of
4500rpm [8.5] | 6000rpm [11] | 62??rpm [8.5].
This i considered ok since i had the dp, mp, and intake.
Now my boost pattern is very low.
4500rpm [6] | 6000rpm[8.5] | 62??rpm [6]
I was under the impression that when changing to a catback exhaust i should be prepared for boost spikes. (hence a new ECU). Any suggestions on why my boost pattern is so low. I did check to make sure the intake elbow was on properly after changing the plugs an wires, and the hose from the intercooler to the elbow is fine. Any suggestions ?

 

yeah sounds simliar to my old boost problem. Sure the piping is secure but have to checked for tear in the connecters? Take a look at the piping connectors, one could have a tear in them that is causing the lower boost.

On another note, your not gonna bet boost spikes from a cat-back, those are from a MP and an aftermarket ECU won't protect against them.

 

Defiantly a piping issue, don’t just look at the coupler, pull it off and check. One note w/o the upgraded ECU you might want to leave it.... except your motor might be sucking in a little dirty air. If you would fix it now you probably would see 11-13.5-11 which wouldn't be that bad with an aftermarket ECU. If you had the stock motor you would run lean and boom. 1000$ for an ECU isn’t bad compared to 3000$ for a motor.

 

I'll check the couplers today. The couplers you are referring to are the ones from the intercooler to the elbow, and the turbo manifold to the another elbow and the the elbow to the intercooler? I guess a total of 3 couplers. On a good note, i took off th UIM and found all the hoses to be intact and no spliced vacuum hoses.THanks for you guys replying so quickly.

 

You probably want to check the coupler from the Y-pipe to the plastic crossover pipe. That is the one that goes most of the time.