i have an all stock exhaust on my 87 GT. this might be a dumb question but i was wondering if i left the stock pipes on the car and just replaced the mufflers with flowmaster 40 series if i can still expect a small horsepower boost and a pretty decent rumble. also any other muffler recommendations are welcomed but i only have like 300 bucks right now lol. you can tell i don't know much about exhaust

 

Yes you can replace just the mufflers. Youll need flow tubes (the pipes going to the mufflers), as the factory ones will more than likely be welded to the muffs. You might see a very slight power increase but highly unlikely unless you get an O/R H or Xpipe. And yeah the rumble will be there. And Id recommend that you NOT get the 40 series(2chamber) get the 3 chamber flowmsters. Similar sound and not nearly as loud. I have the 2 chambers (40 series), with an off road H-pipe this somma b!tch is LOUD! Damn near have to yell at my passengers for them to hear me, the 3 chambers (im assuming 50 series) still got a good rumble and you wont be gettin pulled over for loud exhaust.
-P.

 

You can easily go into a shop and have them cut in some Flowmasters, should leave you with change if you have $300. For a few bucks more you can get an O/R pipe. You won't notice a power difference with any muffler.

Man up and get the one chambers. They sound like a bat out of hell from outside of the car but truthfully it's not bad at all in the cab. When I had the stock H-Pipe it was pretty annoying when it would drone, but when I got the O/R x-pipe it helped the exhaust go out the back and now it sounds great.

 

haha have you gotten pulled over with that setup yet?

 

Not even for speeding. And my car is in the shop getting headers put on right now. When I first put the x-pipe on I asked my wife if she liked it, she said it is supposed to sound like that?