Mandrel Bent Pipes vs. Regular Bent - New Exhaust

My 2001 GT has 105,000 miles on it and is need need of new mufflers. I plan on replacing the whole cat back system as the resonator is pretty rusted and will most likely eventually go as well.

Here is the problem and question. My stock GP has mandrel bent pipes. I plan on replacing everything with Walker OEM parts but the bends are not mandrel they are the bent bends with the ridges. Will this make a difference in performance? Should I even worry about this?

Also, Advance Auto's website says the Walker part fits but does not give the inside or outside diameter of the pipe. Does anyone know the diameter? Part #55204 I need to buy clamps for all the pieces as I intend to do the work myself and do not have a welder or even know how to use one.

Thanks.

usually with crush bent piping you want to oversize it slightly, but being that its a grand prix catback it probably wont matter. the cat back breaths enough stock up to around 300 whp to not be a restriction. i would do a 2.5" catback if youre going through the effort and not worry about the crush bend.

walkerexhaust.com

should have clamp sizes for you.

You could get the dynomax system if you can get it for cheap enough for it to be worth it.

its 2.5" mandrel IIRC.

I've been looking for the least expensive option and have found it with the Walker system. I have to buy all the parts separately on Advanceauto's website but will be around $310 w/o tax for (2) mufflers, y-pipe, and resonator. I will need to buy clamps and such and refinish my existing tips if I can. The least expensive "cat back" system that would fit according to multiple auto sites was a magnaflow which was over $800. The magnaflow is 2.5" pipe however. I still cannot find a pipe size for the Walker. It may be 2.25" - will this make a difference?

I believe the Walker exhaust parts are just mild steel. That is part of the reason they are so cheap. Mild steel will be lucky to last 2-3 years in New York winters before it rusts out. I'm not sure how tight you are on money, but you can get a stainless SLP cat back from lmperformance.com for about $570 shipped. If you don't plan on having the car more than a couple years, go with the Walker system. If not, it will be worth the extra cash to go stainless.

I've been looking at this one for a while now. click me Otherwise, last time when I "made" my exhaust... I ordered muffs/y-pipe/resonator from summit, but had a buddy weld it together. Now thats rusted to **** and needs replacement.

Walker is definately mild steel, perhaps aluminized aluminized, but thats it. Maremont is the same way, but poorly made compared to walker exhaust.

I wouldn't recommend the SLP system due to the fact that it lacks a resonator.

Look for something with a resonator.

Or get the ZZP one without muffs and get your own if you didn't want anything louder.

I just received a quote from Cole Muffler & Brake for an AP catback system w/o tips. They have all 2 1/4" pipe, mandrel bends and will clamp everything together. The resonator and muffler have a lifetime warranty and the pipes are one year. The total for parts and installation was $395. If I wanted to buy the parts only from them it would be $365 but no warranty on any of the items.

Just to get a comparison I called Monro Muffler & Brake and they had the exact same system w/o tips installed for $907!

Anyone know why Cole can get and install for so cheap????

Shoot... One thing I didn't ask is what style the system components were. I'm assuming they will give me the cheapest stuff AP has. Will it be any good and hold up to WNY winters?

they quoted you so high because they really didnt want to do it.

Pretty much...lazy shop...which means lazy work and crap results.

When I had my resonator replaced (with the Walker), I considered having the entire catback done but my mechanic said I didn't need it. The piping looks rusty but it's just on the surface and it's otherwise in good shape. This is a Maine/Mass winter driven 2000 GP with 115,000 miles.

Just thought I'd mention it because there may be no need to replace it.

Yet mine is an 02 and when i bought it a year ago it had non factory exhaust on it and it fell apart earlier this year.

That suggests both the stock and the aftermarket failed in 8 years.