On my 91 L98 I am having big problems installing the magnaflow cat back system. Iverified it is the correct part number for the cat and cat back system. Everything fits perfectly other than the rear Y pipe. If I center it up so the gaps around the spare tire carrier and spring are both even and enough room the distance to the end of the body to the end of the Y pipe is 2 inches wrong. The passeger side muffler tip is flush with the bumper and the drivers side sticks out 2 inches.

Magnaflow told me to push the pipe sideways and it will fit. If I push it enough so both mufflers are about 1 inch out from the bumper and that makes sense then the pipe is very close to the spring and hits the spare tire carrier on the passenger side. The mufflers are on an angle as well. If it helps the hole that was drilled for the strap hanger in the middle was about 1 1/2 inches too low like they welded it on upside down. The hole needed to be on the top rather than the bottom. Without doing that the pipe hit the rear end.. I redrilled that and got the height right.

I am up for any and all ideas. I am thinking the wrong Y pipe was boxed up or the mufflers fit something else that uses a different Y so the mufflers are right and Y pipe wrong with the wrong label on the box?? Also in the pushed over position the mufflers are on an angle sort of aiming at the drivers side headlight.

Thanks in advance for any help,
Dave

 

Sounds like a defective part.

 

My thoughts exactly. While all is made very nicely welds nice and everything else very nice it just does not fit. Either the Y pipe is wrong or the labels is. With a shop as big as theirs and the number of different part numbers seems easy to do. I hope they pull through for me as I wanted to go on a cruise this weekend to New Hampshire already missed the once ayear Corvettes only car show locally. I was putting on the new exhaust for it to buff up my 91..Go figure.. BTW Magnaflow tech has been very patient hope the second try before this weekend goes well..
Dave

 

I'm not sure, but I don't think Magnaflow makes another Y pipe for a C4.
LT1 is an axle back, and I don't think they have a kit for pre 86.
I had no problems with mine, if you like, I can take a few pics so you can compare.

 

Any and all help is wildly appeciated if not a super big task please do send pics.
Dave

 

When my '90 L98 Magnaflow cat-back arrived and did not fit, I called the vendor and they overnighted a replacement. My problem was the "Y" pipe would not clear the oil filter.

 

I took a few pics, but the ones were I just stuck the camera underneath, didn't show anything useful. Without jacking it up, I really can't get any useful pics.
Here's 2 that might be helpful.




Looks like I need to get under there and do some cleaning.

 

i had problems with my front Y-pipe from magnaflow for my 90 coupe - it did not fit without some minor rework. the struff looks quality, but there were fitment issues. i installed a corsa catback and as far as quality and fitment - corsa is top shelf hardware!

the problems with the magnaflow front y-pipe were:

the exhaust manifold flange holes were too large. so large that the exhaust manifold nuts damn near pulled through the holes. the spread on the y-pipe was off (where it mated to the exhaust manifolds), somewhere around 3/4 inch, and magnaflow got their ID/OD's mixed up where it attached to the main cat - i had to expand the y-pipe exit about 1/8th inch to mate correctly to the magnaflow cat. some people would have sent the stuff back, but it was worth the (rework) effort not to go through the hassle of sending the parts back. magnaflow needs to check their engineering drawings and hire some QA people (or fire the ones they have...)

 

Thanks for the pics that is what I thought it should look like about an inch below the rear end and down the center is where the pipes had the most clearance left and righ between spare tire and spring. You have inspired me to remove the spare tire and carrier do you have to add anything back in for spare tire delete? Sure looks like a lot more room to work under there without it and doubt if I would bother to change to an 18 year old tire..
Dave

 

How do you clear the e-brake cable? My 91 has abou a 1 1/2 dip down after the cat and then runs level to the ground. The Magnaflow goes straight back off the Cat and hits the e-brake cable actually pushing it up even when i let it droop to clear the rear end by an extra inch.. The no spare tire has to help in the rear I am sure and will pull mine off while up in the air. Looking in the usual catalogs it seems everyone with a pic of a 91 Y pipe specifically shows the drop after the cat as does a GM picture of the pipe. I just do not see how this maganflow Y pipe is going to fit a 91 L98 couple at least not mine...

Any ideas for exhaust besides Borla and Corsa? Not going there in $$$$
Dave

 

I will jack it up today and get you some better pics.

 

Thanks for the help just e-mailed a gorgous woman that we are no going cruising this week end..sigh.. not good..

 

Here's a few more pics >> http://members.shaw.ca/agent86/Magnaflow/

 

Thank you very much for the pics! My e-brake cable is about 1/2 lower than the outlet on the cat and the factory Y pipe has a droop to clear it. The cat outlet clears the driveshaft by about an inch while on jackstands though see no issues with that as none of the things move so an inch seems as good as a foot for that. Looking in a lot of the usual catalogs they show this droop as well in their Y pipes (rear). I did remove the spare tire I bet that is 35 lbs of something I will never use though have to say it still had plenty of air in it no cracks in the tire either but things would have to be pretty despirate to use it i think. I can't follow how you have such a low cat outlet and i do not. My front Y pipe is in a factory hanger so find it hard to believe it is in the wrong place. I have noticed searching that a lot of companies list exhaust parts as 91 only so this whole problem might be a 91 only issue..
Dave

 

Put the Borla system on this morning pretty much fell into place! No rattles sounds nice a bit loud for very long trips I would think but it now sounds like a Corvette.. The Y pipe did have the correct dip to clear the e-brake cable as well. I liked the looks of the Magnaflow system but it is weird the pipes all seem to be made so you have to use the rest of thier own system or build custom.


Brakes are next I have I think all the parts needed to put on the J55 fronts with new rotoes all the way around and thinking Hawk HPS pads for street use and good stopping power cold. The cheap pads on it now will not even set off the ABS..