Ok, I'm going to try this again. I want to get a cut out for my brother's 89 L03 for Christmas but I looked underneath and couldn't find a good place to put one. I was hoping ya'll could tell me and/or give me some pictures of where yours is. Thanks

 

just before the muffler which is actually too far back to make it sound good BUT it did make a 18 Ft/lb difference on the RW Dyno...

 

right under the passenger seat in the "I" pipe, also equipped with a McCord Power Plate

 

thats the only good place to do it is where the cat goes, you have to do it before it , seems like a waste to do it after the cat. A lot of people do it after the cat since its easier . but do it before the cat , either remove the cat or move it in the middle , in the i pipe .

 

Mine is a single 3" cutout, just after the Y-pipe. Its a perfect spot for it IMO, because its right near the outside of the car, so theres no crawling around under the car to uncap it, you can reach it easily from the side of the car. I used 9/16 stainless nuts because its easier to get them tight enough to seal well (compared to wingnuts). I just keep a 9/16 box end wrench in my glove box for when I want to uncap it.