My CP-E LTH Experience (And Fix)

NOTE: This is sort of long but it explains everything that I went thru, cliff notes: I am very happy with them! But take the time to read to get full grasp of what happened.

So, I was on the boat about buying headers about two months ago (around Thanksgiving) and finally decided to go with the cp-e LTH’s because of various factors: design, the company behind them, looks, etc. I was iffy about the sound but I said “I can get over it” LOL, yeah right!

I received my headers the week after Thanksgiving and I went that same weekend to STRK (great group of guys and very helpful) to get them installed. The deal was I would trade them my CMD for the install and they would give me back some cash. That didn’t end that way, though I don’t regret it, they got me home that night with an excellent fix!

Install:

So, removing the OEM headers was a pain because of the heatshields and having to lower and raise the car just to get enough room (from top or bottom) to get to the nuts on the head studs, especially the ones near the front of the car. After the OEM ones were off, we determined that wiggling in the LTH would work but a lot of wiggling and banging would occur so the next best thing; the motor-mounts were unbolted and the motor was jacked up just about two inches. This is needed mainly for the driver’s side because I believe there is a bar that goes diagonally that makes it very difficult to get in there. So wiggling in with the motor raised a bit works like a charm, but getting the nuts in was a little difficult but it was eventually manageable.

Once the headers are in, you can lower the motor and bolt up the motor-mounts, and onto the x-pipe (my favorite); as long as the catback is lowered or off the hanger to be able to wiggle the x-pipe onto the slip fit. I have a Stillen catback that I love but had some fitment issues with it cp-e x-pipe.

Fitment Issues:

The Stillen catback is supposed to bolt to OEM downpipes, the cp-e LTH are supposed to bolt to OEM catback, “where is the problem?” everyone asked, the answer: the catback, plain and simple. What happened was that the x-pipe fit perfectly with the headers but once it gets to the x-pipe on the Stillen x-pipe (yes I had 2 x-pipes), one flange would not sit 100% flush but would line up, and the other flange would be off alignment, but quite a bit, about an inch or two. Thank God, I was at STRK and they were able to cut and reweld (TIG) the cp-e x-pipe and make it fit to the Stillen catback. Here is source of the problem: the Stillen bolts to the OEM downpipes, but the OEM downpipes have flex pipes on them so there is some room there for error, sure other companies don’t have this issue but we are not here to determine that.


Pics of the fitment and the fix:






The issue fixed but even tightened all the way one of them still has a bit of separation:




After Install

So, after about 7 hours of work and money lost from the CMD (I had to give it to them with no cash back because of the cutting and welding, not complaining but wasn’t expecting to run into this), they are finally on. I drove the car around after it warmed up and they sounded just fine.

The Noise

They actually weren’t as bad as I thought and the car felt pretty nice. I drove the car for the next few days and started to notice the rasp at 3K RPM, I guess the honeymoon period expired, LOL. The noise went from ok-that’s-loud, to bad, to unbearable after a day or two. After thorough analysis at the dealer with friends of mine (video below) we determined it was the runner pipes vibrating against each other and transferring the sound to the collector. The pipes probably rattle inside the collector as well, but that is to be determined as of yet. Here is a vid of the pipes being banged making the noise, (yes I am aware Ark mocked cp-e and me on this, but that is to get back to later)…



The Fix

After more banging and too many strange looks on the street, I ended up going to one of the best muffler places in Miami, Miami Muffler. I figured they would have all I need in stock and their pricing is pretty good. So about 3 weeks ago I went in and told them what I needed done (to put my secondary cats back in eliminating the cp-e x-pipe) and I explained to them the issue with the noise. When the cp-e x-pipe was removed, banging the collector made the noise extremely loud and tinny, like thin metal. They had no problem making pipes that slip fit onto the cp-e headers and bolt to my secondary cats which in turn bolted to the Stillen catback.

They then welded some small metal tabs to the runners (two on driver’s side, and one on passenger side where the pipes were too close), attached the secondary cats, and put everything back together. Banging on the collector made A WHOLE LOT LESS noise even though just a little bit of noise was still there. Here are pics of the welded tabs, brackets, whatever you want to call them:

Driver’s Side:



Passenger Side:




Aftermath

As soon as I left Miami Muffler, I got on the gas and as soon as I hit 3K RPM, I was relieved to hear NO RASP! I got on the highway and on partial throttle the car almost felt like boost was coming on, LOL, the added backpressure was a definite plus, and the best part is that the noise was 90% better and no bad catless smell! Yes, there is still some rasp letting off the gas and at certain RPM, maybe the fix for that would be to weld some more tabs near the collector because I still think the pipes may vibrate there. Nonetheless, I am still very happy with my LTH, the performance is there, says my butt dyno, but I am also at sea level so that may make a difference from others, and I just REALLY want a reflash now!



I am so relieved and I know I have taken a long time to get this out but I really hope it helps some of you out there… I would like to thank the community for the support, Dmitriy at cp-e for the EXCELLENT CUSTOMER SERVICE, STRK Enterprise, all my buddies at the Hyundai dealer, and Miami Muffler!


As Requested: Pics of my header/exhaust setup