I run the cap on my neck and run a filter off of my valve cover like this. You can see the filter in between the throttle body and compressor housing. I'm not running a catch can though. I just run filters on both covers.

 

That filter on the valve cover port will work perfect. Pretty sure that is a 3/8's barb on the pass. side valve cover. I will get one coming. Thanks.

 

I had same 3/8 breather filter on pass valve cover with breather on fill cap, too. There was too much blow by. Oil was splashing from the filter on pass valve cover. Had a RX Catch Can w/ Dual Check Valve which did not work. Poor catch can did not collect any oil and poor customer service. They did not even respond to my complain. So, I ditched everything after reading about people having problem and return it to fix the issue.

Now I have MM vented catch can -8 fittings and 1/2" hose clamped to both 3/8" valve cover stock ports. No breather on fill cap, just stock cap with neck removed.

Now, new cc is working good. No more all on valve covers or fill cap. I drained the cc twice so far and it has some oil in it. Good sign it is working but I think I have too much blow by cause the engine is consuming oil. Same thing with my previous NA engine.

You can try the breathers but if you have oil splashing from the breather filter on you engine, you will need vented catch can connected to both valve covers, to be safe.

 

U need to vent ur valley pan to. These engines r terrible for blow by with out a valley pan vent.

 

No valley cover vent on Gen III blocks. Mine is 2003 same as OP.

 

I have seen quite a few setups where people have drilled a fitting into the valley plate. Then just put a "t" in to your line from the pass side to the catch can.

This is how I have decided to try my setup. #8 from each valve cover and another #8 from the valley plate into the passenger side line all to a vented MM catch can. Also going to run a line to the intake tube in front of the turbo then back to the catch can for vacuum. I will see how this works.

 

On vented CC like MM, the pre-turbo vacuum line will not be effective since it will draw air through the CC top filter instead of pulling from the engine.

To be able to use pre-turbo vacuum line, you need sealed catch can (not vented) and you will need a third port on the cc with check valve connected to intake manifold for vacuum when off boost.

In my opinion, best setup and simplest is just to use the vented MM catch can connected to both valve covers. Leave the pre-turbo. At idle, on boost and off boost, both valve covers will vent to the vented catch can with no problem. Except, you will not have vacuum source applied to the valve covers, it will vent naturally at all times.

 

Do you have the MM catch can? I do and under vacuum it is sealed. It has a rubber valve beneath the filter that will open up under positive pressure.

 

Yes I have MM cc. I did not notice anything under the breather filter. I will have to remove the filter and check it.

Are you saying that one port on the CC can be connected to pre-turbo while the second port can be connected to only one valve cover or tee-ed to both valve covers?