Hey, Im lookin at getting a high-flow cat and a flowmaster 40 on my '01 blazer. I am going to keep the stock pipe,up the the muffler at least, and maybe do somthing diffrent off the new muffler. My question is what size cat and muffler do I need to fit (over or into) the stock pipe so I can weld it on. I can find the stock size OD anywere online. thanks for your help

 

the stock pipe size is 2.25" and if you plan on going bigger i would suggest no bigger than 2.50" any larger without the proper engine mods will cause you to lose power.

 

Just crawl under there and measure it to be sure. I would get a cat that goes over the stock Y pipe and from there go as big as you can all the way out the back. Say maybe 3".

 

So would the 2.50 cat go over the stock pipe(on both ends) and be really sloppy, or will it be a nice fit over so you can get a good weld. Is it 2.25 all the way back to the tailpipe. thanks man

 

im not sure if the 2.5" cat will fit or not youll have to measure that one, and yes it is 2.25" all the ay to the tail pipe.

 

I am going to put a high-flow cat in place of the stock one, and put a flowmaster 40 muffler with a single 2.50 tailpipe off the back to a dual tip. Thats the plan so far. do you think it would sound better(diffent) with the 2.50 tailpipe, or sould I just save the money and leave all the stock pipe in and just put the new muffler in it???

 

ive got 2.50" pipe from the cat-back, but the .25" difference wont have any real noticeable affect.