The Big Mouth does a great job of providing the air needed to the radiator. It does not hang as low at the stock air dam but it does hang some. The Big Mouth is metal and would not respond well to running into a curb however. I had the Big Mouth and the stock air dam pieces on my recently sold 92. I think the Big Mouth would provide all the air needed for the radiator without the stock air dam pieces. Over the months that I drove it (daily driver) with the Big Mouth, I never scraped it on any curbs, driveways, dips in the road, etc., that I normally scrape the regular air dam. I also paid close attention to parking lot curbs, etc. and made sure I kept the nose away from them when parking.
One more note: if this is a big issue for you, then never upgrade to a C5 or C6 as their air dams are lower and scrape a lot more often than the C4 air dam ever did! I just treat them a regular replacement items and press on, replacing them when they look a little too worn.