will I be able to pass the smog test? stock cat, with cat back exhaust, if needed I can switch to stock exhaust when the time comes.

 

you'll have 0 issues passing smog with a catback exhaust

 

I've been passing smog with intakes and exhaust, I even passed with the Stillen SC kit

 

I'll be honest, it was enough of a pain installing it with the bumper off, I wouldn't have any interest in saving the 30 mins it takes to get the bumper off as I'd waste it on the back end anyways trying to line up pipes and screw on clamps neatly. I also have a coupe so there may be differences in the grille opening size.

 

I also came across this https://www.myg37.com/forums/intake-...lp-needed.html I guess I need to cut the air duct hole bigger?

 

Never said is was easy just saying I didn't to take it off and I didn't have any issues with the clamps or anything, I put the elbows together before I put them in, the pushed them through the rad support holes, there's enough room to to that .

 

are the air duct hole big enough for the tube to go through? any cutting needed?

 

No you have to cut the Duct holes and make them bigger..i didn't remove my bumper either when i put mine in

 

Not necessary but it's recommended. Otherwise, you end up with a pinch at that spot in the intake. For maximum airflow (and max power) you want as much air coming through as possible. By having it pinched in that spot, you're creating a bottleneck effect.

 

It doesn't technically "pinch", it deforms. I don't see a way that the total diameter is reduced due to this, thus the airflow would remain the same. It's a circle shape being pressed through a rectangular opening. Basically, that section takes on the rectangular shape, that's all.

 

any tips on how to cutting the air duct? tools that required?

 

Dremmel.

 

Not true.

Area of a rectangle that has a 12 inch perimeter (4 in x 2 in) has an area of 8 square inches.
The area of a circle with a 12 inch perimeter is 11.46 square inches ... a big difference.

The 4 inch x 2 inch and 12 inch perimeter are arbitrary numbers, not sure of the exact measurements, but the principle is the same.

 

The total cross sectional area is the same. You're looking at it the wrong way. If you take a circular cross section (the silicon tube) and you deform it to fit inside a rectangular passageway (air duct), assuming that the tube does not bend inward at all, it will have the same cross sectional area as before, just in a different geometry.

The only concern going from a circular pipe, to rectangular, and then back to circular again, would be the small degree of flow separation. The intake charge wouldn't necessarily speed up or slow down due to the change in geometry, but the effective cross section might be slightly smaller due to flow separation through the rectangular portion.

 

Im not trying to be rude, but that isn't true. Even if you slightly deform a circle it has less cross sectional area.

Take a circle with a 4 inch diameter it has a cross sectional area of 12.57

That same circle deformed to an oval shape (3 x 4.88) has the cross sectional area of 11.52, so about 1 square inch less. The more you deform it, the more cross sectional area you will loose.

A circle is a more efficient shape to move air through than an oval or rectangle.