Here's how I see it and feel free to comment. I promise my feelings will not get hurt if I'm incorrect.


2" intercooler pipe 12 feet in length = 452.16 cubic inches
24x8x2 Intercooler = approximately 231 cubic inches
Intake manifold = 155 cubic inches
Total Volume of Intake System in cubic inches = 838.16 ci

3" intercooler pipe 12 feet in length = 1017.36 cubic inches
24x24x3 Intercooler = approximately 1037 cubic inches
Intake manifold = 155 cubic inches
Total Volume of Intake System in cubic inches = 2209.36 ci

A stock 2.3T upper/lower intake manifold is approximately 155 cubic inches.

Let's assume this 2.3T can flow 186 CFM at 3200 RPM. 186 CFM is much lower than I would normally see on a stock 2.3T setup. Let's also assume 360 CFM at 6000 RPM.

Lag Time in Seconds =
(Volume of Intake system in cubic inches/Flow Rate in CFM)*(60 / 3456)

0.313 Lag Time in Seconds = (838.16 ci / 186 CFM) * (60 / 3456)
0.162 Lag Time in Seconds = (838.16 ci / 360 CFM) * (60 / 3456)

0.824 Lag Time in Seconds = (2209.36 ci / 186 CFM) * (60 / 3456)
0.426 Lag Time in Seconds = (2209.36 ci / 360 CFM) * (60 / 3456)

The 2" pipe with smaller intercooler has 0.511 seconds of less lag at 3200 RPM than the 3" pipe with the larger intercooler. At 6000 RPM the 2" pipe with smaller intercooler has 0.264 seconds of less lag than the 3" pipe with the larger intercooler.

186 CFM can travel at 63 feet per second in a 3" tube.

I highly doubt anyone could notice 0.511 seconds of lag time.