I have a 2003 Max and I have a bunch of questions. I want to tune it up, but I'm not sure where to start. What is the block off plate for? I like the sound of the Megan Racing Exhaust, but who does a good job in Maryland installing them? Is their a Megan Racing Intake as well? Is Megan Racing products quality products? I only have 72,000 miles on my car and want to replace parts that go up with racing parts.

 

All of these parts can be installed by yourself.

 

Tune up:
Buy NGK Oem plugs. You'll need new intake manifold gaskets also as the upper manifold has to come off to get to the rear plugs. Fuel filter is "non serviceable". Air filter is held in by a few clips on top of the air box. Might look into NWP spacers while the intake manifold is off.

Block off plate:
It blocks off the VIAS on the car. There is a butterfly valve on the passenger side of the top intake manifold that opens and closes through the rpm range. It's supposed to give you more torque down low without sacrificing hp up top and vice versa. I blocked mine off with a plate from NWP. Lost a bit of low end but gained above 3500rpms.

Megan intake:
I don't think Megan makes an intake for this year. Several other companies do though. However, many people (myself included) choose to run an highflow filter (I went with AEM DryFlo) and the Ghetto Airbox Mod. Basically you just drill holes prior to the filter to lessen the restriction caused by the stock intake box.

Megan products:
I've purchased many of their products over the years. Their products are decent and I haven't had any issues.

"Racing" mods:
A tune is pretty much out of the question for the 02-03 cars.
NWP makes some intake related parts for these motors. The block off plate, manifold spacers, and a throttle body. All backed up with dyno proven results.
The precats on these are a choke point and fail often. Your choices are to gut the stock precats on the manifolds, or buy headers.
If you're not ready for headers, a Y-pipe will help too. Warpspeed makes one that's reasonably priced.
A test pipe for a 240sx will bolt on in place of the last cat. There is not an O2 sensor behind this particular cat, so no worries of a check engine light. However, if you're in a 'strict' inspection area, you might fail visual inspection.