i have a GSR with dc header and GSR cat.. but i need to smog my car soon.. so i bought a LS cat and it doesnt fit the GSR header... so i was thinkin if i get LS headers with LS cat would that fit my GSR? or am i better off wielding the cat to fit my dc headers... please help

 

Does your GSR cat not work? If you already have a cat and a DC header (which is CARB approved) as long as its a USDM 4-2-1 or 4-1, why did you get an LS cat?

An LS cat will not work because the exhaust and header lengths are different for each year. The only cat that would work is a cat from either a 94-99 GSR or a 00-01 GSR, depending on the year of your car. However, if your exhaust, cat, and header are from different years, you will have to piece it together so that all of your parts come from the same model. For example, you could run a 94-01 LS header, cat, and exhaust, or a 94-99 GSR header, cat and exhaust, or if you happen to have a 00-01 GSR, you could use a 00-01 GSR cat, and a 94-01 LS exhaust.

As you can see, it is confusing, and that doesn't even consider the different o2 sensor setups depending on model and year. So it would help knowing what year car you have.

 

i gutted my cat... so i bought a new one which is an ls and doesnt fit my GSR DC headers... so i was thinkin if i just weld the cat to fit the headers.. everything would be okay... let me know what u guys think is best.. i need help!

 

What year is your car, and what do you mean by 'doesn't fit', is the flange a different size? is the cat too short? too long?

If you gutted your cat, I would just invest in a high flow cat that Dave from SMSP (username is SMSP as well) could make for you. If you tell him what header and exhaust you have, he can make you a cat with custom flanges, o2 bungs, etc.

 

an ls cat and a gs-r cat are the same size the only difference is the length of the headers, but one thing you are gonna need to do is to relocate your o2 sensor cause the LS is mounted on the header and the GS-R is on the cat, that is the only difference you will find

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 1JDMDB8 &raquo;</TD></TR><TR><TD CLASS="quote">an ls cat and a gs-r cat are the same size the only difference is the length of the headers, but one thing you are gonna need to do is to relocate your o2 sensor cause the LS is mounted on the header and the GS-R is on the cat, that is the only difference you will find </TD></TR></TABLE>

Well, the o2 sensor depends on the year, if you have a 94-95 gsr, you will have no o2 on the header and 1 on the cat, if you have a 96-99 gsr you will have only 2 o2s on the cat, and a 00-01 gsr will have 1 o2 on the header and 1 o2 on the cat.

 

is your gsr cat bad? If you need one i have one. Factory part, 80,000 miles, removed while engine was still stock. I never failed an e-check with it. $75.00 shipped

 

hmm reweld the ls cat to fit gsr headers or just go ls headers.... also i was wondering if LS headers fit on a GSR motor.. would everything just be bolt on?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by purplegsr (Exospeed) &raquo;</TD></TR><TR><TD CLASS="quote">An LS cat will not work because the exhaust and header lengths are different for each year. The only cat that would work is a cat from either a 94-99 GSR or a 00-01 GSR, depending on the year of your car.</TD></TR></TABLE>i was under the impression that the 94-99 gsr's had a shorter cat (~14") than the 00-01 gsr's (as well as ls/gs/rs and itr's)...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dFreezy &raquo;</TD></TR><TR><TD CLASS="quote">i was under the impression that the 94-99 gsr's had a shorter cat (~14") than the 00-01 gsr's (as well as ls/gs/rs and itr's)...</TD></TR></TABLE>

I was under the same impression, I thought the LS, 00-01 GSR, and ITR had roughly 17 inch long cats, while the 94-99 GSR was 2-3 inches shorter. Not sure though.

jdmxxdc2 - if you don't tell anyone the year of your car, and the year/model of header and exhaust you are using, nobody can really help. Of course, getting new flanges and shortening or lengthening piping here and there will also serve your purpose.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by purplegsr (Exospeed) &raquo;</TD></TR><TR><TD CLASS="quote">jdmxxdc2 - if you don't tell anyone the year of your car, and the year/model of header and exhaust you are using, nobody can really help.</TD></TR></TABLE>YES!

Early GSRs had a shorter A-pipe & a longer cat.
Assuming(?) it's an early GSR, the O2 sensor is in the cat. So get the LS cat modified like this...
Extend the inlet end to make it longer, with a flange to match your header. (Don't need an LS header.) Have an O2 bung put into that extension. Don't modify your headers since you might want to put your other cat back in.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by purplegsr (Exospeed) &raquo;</TD></TR><TR><TD CLASS="quote">I was under the same impression, I thought the LS, 00-01 GSR, and ITR had roughly 17 inch long cats, while the 94-99 GSR was 2-3 inches shorter. Not sure though. </TD></TR></TABLE>i'm fairly certain this is correct actually. my 01 gsr has a ~17" cat.