Application:  92-93 Caprice LTZ & All 92-93 L05 5.7L B-Body Wagons.

Description:  The air box mod (pictures below) was accomplished at the same time that I removed the stock exhaust from my L05 equipped '93 Caprice 1A2 Wagon for the more free-flowing system from a L05 equipped '92-'93 Caprice 9C1 Sedan.  As a result, I can't make any statement as to the effectiveness of the air box mod by itself.

As for the two mods combined, that's a different story.  In January of 2001, my stock Y-pipe broke off just in front of the catalytic converter.  Welding wasn't recommended, so I went looking for replacement parts.  At that time, I had no idea that the L05 engine and exhaust system in my 1A2 (Special Service Vehicle) was inferior to the 9C1 (Police) system.  Well, it is!  Not only in the exhaust area, but camshaft, injectors, and ECM programming, too!  That's another story, for another day.

The 9C1 Y-pipe (GM, Walker) has larger tubes and a 3" exit.  The catalytic converter (Discount Converters Ltd) has a 3" entrance and 3" exit.  The pipe from the catalytic converter to the muffler (one piece) necks down from 3" to 2-1/2".  I then used a non-resonator system (Walker) for a Wagon from the muffler to the rear of the car.  The exhaust system now has a nice subdued tone, slightly louder than stock.  Combined, the exhaust and air box mod really woke up the L05's performance!  If it wasn't mine, I wouldn't have known it was the same car!

Parts Required:

Y-Pipe: 

Walker - Part # 40315  $62.06*.  3" Clamp - Part # 35794.

GM - Part # 10234907  $85.42*.  (Came with my 1A2 when I bought it.  Original had repaired crack)

Catalytic Converter:

Discount Converters Ltd.  Part # 9118.  $108.95.
Walker  Part # 15622.  $131.00*.

Exhaust System:

Intermediate Pipe - Walker (Police).  Part # 44314.

Muffler - Walker (Police).  2-1/2" In & Out.  Part # 22393.  Ultra-Flo SS Part # 17288.

Tailpipe - Walker (Resonator Delete).  Part # Not available.  Will post as soon if I can find it.

Clamps & Hangers - As Required.

* 2001 Prices.

Air Box Mod:

Dremel tool, die grinder, cut-off wheels.

Assorted files to remove sharp edges.

A lot of metal was removed.  I thought about removing the part completely, but then there would have been no pressure exerted on the bottom inside of the air box to seal it to the gasket on top of the throttle body.  Looking back, I would have probably have left extra metal (2 red arrows) to strengthen those posts.

Sort of looks like 2 Indian Cobra's facing each other?