Just curious if anyone else has or had this problem. I purchased a replacement LM1 back in 2009. I already have a LM1 on my car but brought a new one when the new 4” tips were released. I opened the box this week because I planned to put it on this weekend and I noticed it is aluminized steel. The metal looks different than the LM1 currently on my car. The new system is definitely not stainless steel like it should be. To verify I used my pen magnet to check the metal, the magnet stuck right to the new LM1 but not the old system. I thought SLP only made their systems in stainless steel so I’m surprised to see this. I emailed them and asked if they would correct this; I’ll see how it goes.

Even says right in the description stainless steel: SLP LM1

 

Keep in mind that if stainless is non magnetic it is due to the nickel content, not the lack of iron. Stainless steel is ferrous (contains iron). Some alloys do not have enough nickel to interrupt the physical properties that keep the magnetic lines of flux traveling through the metal. It could still be stainless depending on alloy.

 

What he is trying to say is simply this: I have magnetic tools stuck to the sides of my stainless tool box. Generally speaking, high quality 300 series stainless will not be magnetic, while 400 series which is considered a lower grade, but is still far superior to steel in corrosion/rust resistance will be magnetic or somewhat magnetic. So, your magnet is not the end all be all. Why don't you post a pic and see if we can tell, take some close ups of the welds if possible.

<<X-stainless welder.

 

Thanks, understood. The reason I did the magnet check is it was something KOOK's had me do when I thought they sent me an aluminized y-pipe when I ordered a stainless steel one. KOOK's corrected the problem without question.


Thanks, I follow what was said. The grade of metal is definitely different than my old LM1. A magnet will not stick to my current LM1 but will on the new one. The metal is also a different shade. On the exhaust it says 409 aluminized, which after doing some research I guess it is stainless steel. I also see that 409 aluminized stainless steel is just stainless steel dipped in aluminum. However, as I said the new system is different from the old one. The old one actually looks much nicer as it has a nice shine to it. The new one is dull like the Corvette's x-pipe is from the factory. I guess I was expecting it to be like my current LM1 but got something different.

Pictures:

 

I beleive that all of SLP's Vette systems ARE 304 stainless, whereas NONE of their f body systems (at least the 4th gens) are 304, but ALL 409 (including their y-pipe).

As far as I know ALL of Magnaflow's systems and mufflers are 409 stainless, except for their tips which are 304.

 

Yep, just a lower grade with an extra coat for added longevity. Price difference between grades of stainless can affect overall price of the product by quite a bit I would imagine. That's likely why they did this, to avoid a significant price increase. Down in the south that would last forever, the north, who knows.

 

I had a similar experience where I purchased my SLP LM1 in 2002 or so and 10 years later I was lightly rear-ended bending one of the tips and the body shop replaced the whole system.
The new LM1 was the aluminized version which and was visually different from my original LM1 (dull on the new one vs shiny on the original). I too did the magnet test...didn't stick to the original but did to the new one. I finally got a confirmation from SLP that they did change the material they use to make the exhaust. It is still "stainless steel", but as had been said by others, it is a different grade that is also aluminized. I forget the specifics, but grade 409 sounds familiar.

Ultimately it's under the car so I don't mind too much and it still sounds awesome.

 

I call BS on SLP, I had a Loudmouth catback not too long ago and it's clearly regular old aluminized steel. The muffler and tips were stainless but the rest was not. Ultimately it shouldn't matter that much unless you're driving on heavily treated roads in the winter. I've got a Pacesetter ORY on my car and drive it during the winter in Virginia and it hasn't gotten rusty, at least not yet. But yeah, I think SLP is being less than honest on that one.

 

Why would they lie? That's a pretty big accusation from someone who hasn't posted any actual facts to prove otherwise.

 

The one I bought had "aluminized steel" written on the pipes, I didn't know there was such a thing as aluminized stainless steel. Perhaps it is still stainless but it certainly will be more prone to surface rust than 304. Not that big a deal unless you live up North, but still disappointing that SLP went cheap on their materials.

 

I dug up some old e-mails I had about this from 2010:

From Dave Hamburger @ SLP:
"The piping is still stainless, it's been given an aluminizing process that helps brighten the finish and keep it brighter longer."

I then asked if the pipes could be polished to look like the original design and received this response:
"If you polish the AL stainless, you'll polish the AL off of the tubes. Brasso should keep the pipes looking like new."

From Brandon @ Maryland speed:
"SLP does not have any plain steel at their facility. The exhaust you received is 409 stainless. 409 stainless is a lower grade of stainless that many exhaust manufactures use (Magnaflow, Bassani, etc). It has more iron in it than say 304 stainless, so it is magnetic. 409 stainless may develop surface rust, but it will not rust through. The AL from what I understand does mean it is aluminized..but it is aluminized 409 stainless, not plain steel."

 

Stainless is rust resistant because of the chromium content and its ability to grow a skin of chromium oxide which prevents the oxygen reacting with the iron. All stainless steel is ferrous which means it contains iron.

 

^^^^ THIS!!!

ALL but the very top tier, crazy expensive exhaust companies (Corsa, Kooks, B&B, Borla<-not even ALL of these anymore either) use 409 now, and NEVER 304, sad as that may be.
The only exceptions seem to be that some of the less costly systems for the y bodies are still all 304, as I guess they feel that they "deserve" the austenitic stuff more than us 'lowly' f body owners do?

 

I have yet to put the new LM1 on. I just did a LS7 clutch swap this weekend and have an open y-pipe for now, sounds wicked with my cam! I can also really feel the cam with the open y-pipe. I think it actually sounds better than the LM1, and no it does not sound like an old open exhaust truck! I also replaced my KOOK's catted y-pipe. The old one had poor fitment, took two hours to get it on the headers and got dented up in the process. They redesigned it and the new one is perfect, the cats have slits for great fitment.

 

All SLP is 409 stainless, and has been for a long time. It is one of the reasons SLP's Vette systems cost less than $700, where Corsa/Borla ect are over $1000. Honestly, in most applications, you would never even know the difference.

Keep in mind, SLP was sold in May and moved to Michigan, so the metal is likely coming from a different mill, which is why it looks different.

 

Just an update: I called SLP and they confirmed it is now aluminized steel. I am having a custom system made that will be out of 304 stainless steel, not by SLP. My new system is similar to the SLP Loudmouth exhaust but will have no resonator in the intermediate pipe.

 

SLP was sold to Roush. The reps are all new, and not completely up to speed. The LM is still 409 stainless. It still even says stainless in the product description.

http://www.slponline.com/product/310...Dual-Tips.html

 

I talked with SLP today and they said the system is now 304; I called because I was going to ask if they could make me one in 304. Anybody purchased one lately who can confirm this? Thanks.

 

i bought the Lm2 a couple weeks ago

still says aluminized steel right on the pipe

the car will never see winter so its of no worries to me

 

Getting my two SLP Loudmouth 1 resonators put on tomorrow in place of the dual bullets that came with my Texas Speed duals. They've been sitting in the garage for some time now, and one has some surface rust on it. Nothing bad, but the other one is completely fine looking.