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For three days i have tried to install my new and not destroyed ceramic coated headers. I ordered 1 3/4 with the high flow cats. Passenger side required me to grond down the bell housing. The driver's side went up in under a minute. Here is where my problem. The y-pipe will not slide onto the header on the driver side. Why? Here is why, why I attempted to slide it on, there is a substantial gap between the header and y-pipe. Along with that there is no room as the y-pipe is already full against the floor pan.
I thought, let me unbolt the headers and put everything together. I managed to do that only to have the headers now unable to bolt back up. This again is due to driver's side y-pipe completely pressed against the floor pan. Only mod I did prior to install was, spohn solid motor mounts. HELP!!
I am going to take a few pictures for comparison. ARH is sending me out a completely new set. Even offered to pay to have them coated, since I paid to have it done via 3rd party. Spohn told me today the mounts are stock heoght and will not raise the engine. I'm not so sure.
After two more days I got the puzzle together. In my case, Spohn solid motor mounts do work with ARH 1 3/4 headers. The fit is so tight my y-pipe hits the floor. My next step will be to wrape that portion to deaden the rattle. I also have a prothane transmission mount. There is CONSIDERABLE vibration in the cabin now. This is mainly at idle. The rasp in my LM1 is practically nonexistent. The car is running rough trying to relearn the fuel trim just like Steve said. So far the tune he did is great. I'll take some pictures after I get off Friday.
Yes, Spohn says it's solid engine mounts do NOT cause the engine to sit higher, but you're far from the first or last to have their engine sit higher, causing clearance issues with headers. I've been hearing about people having this issue with the Spohn engine mounts for probably 10yrs. IMO, I seriously doubt there's something wrong with the headers, it's most likely the engine mounts.
Last edited by 99Bluz28; Oct 26, 2014 at 04:12 PM.
Unfortunately, people have had their problems with Spohn about fitment and they always say it's you, not them. I too had issues with Spohn.
I'd hate to say it but if your problems persist, maybe modifying the Spohn mounts (cut them and have them welded a bit shorter) or replace the K-frame entirely with another brand.
Thank you all for your insight. After having Bill's Muffler in Dallas weld my LM1 in, the y-pipe banging has subsided considerably. Now Steve from Frost is working with me on my tune. I'm getting P0171 and 0174 codes. Hopefully it will work out.
Originally Posted by Paul Bell
Unfortunately, people have had their problems with Spohn about fitment and they always say it's you, not them. I too had issues with Spohn.
I'd hate to say it but if your problems persist, maybe modifying the Spohn mounts (cut them and have them welded a bit shorter) or replace the K-frame entirely with another brand.
Thank you all for your help. ARH sent a replacement set and they went in smooth as butter. I ended up sending the the PCM back to Steve for re-tuning. Apparently the MAF was the culprit. Now I am running SD on her.
I ran the Spohn solids as well. It DOES raise the motor approx a 1/2 inch. It was enough that I had to notch the subframe rail on the drivers side, and grind some completely useless material away from the K member. The k part is pretty common...
I wouldn't trade them anything though. I loved them. Of course Spohn says it doesn't raise the motor... I'd guess they never did check after putting them into production. They'd see it immediately if they did.
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ARH header Install Nightmare 
