Hey guys...
I'm about to install an Apex N1 single exhaust on my 89 GTU, and I'm thinking about also getting the mid-pipe to replace the cat converter. This car will be used on the street, pretty much every day, and I was just wondering if the lack of a cat would make un-streetably loud. I think I can work around the state-inspection legalities without too much trouble, but will I regret installing the midpipe if I drive this car every day?

 

Having just the N1 Single would be incredibly loud.

 

If you want noise reduction with good sound, get the GReddy power extreme exhaust from rx7.com. My car came with it, and is a very nice sound, yet very quiet. acctually, all the sound is from the engine itself and hardly any from the exhaust. but, 2 downsides, for you it is dual exhaust, and it is $900, but worth the money in my opinion (although I only spent 1k on my car and it came with it)

 

Mine is the same way with my Racing Beat setup-you can hear the engine over the exhaust, especially since the cone filter makes the engine a bit louder.

Personally, I wouldn't put a single exhaust on a NA car. It's just way too loud. Since you can get around the cat, look at sticking a presilencer in there, that would help a bit but I would seriously consider dual mufflers.

On the other hand, I've heard a few N1 singles on some Turbo models... they are LOUD, but the owners like it that way.

 

I had the RB header with 2.5" test pipe, 2.5" piping all the way back to ebay BOMZ GT style mufflers. Sure it was extremely loud, but I got used to it and it didn't bother me. However it bothered my neighbors and eventually may parents made me "quiet it down" so I threw in a third muffler in place of the test pipe. The way it is now it's a lot less quiet and my neighbors dont care anymore.

 

If you have the stock manifold on it should just barely pass. With headers, no way. You'll need a pre-silencer at the very least. I would advise running the stock cat until you can get a presilencer or high flow cat.