3inch catback guys

old01cobra

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I've got the 1 3/4 too 1 7/8 to 3inch collector headers mated to a 3inch xpipe with the reduction to bolt to the 2.5inch catback. I made 460rwhp NA so that puts me at about 520-540ish flwhp. Just curious the guys that went from 2.5 to 3inch catbacks did it help?

Would like too here some real dyno gains.... Kinda thinking 2.5 is still enough for me but maybe some one can shed some light for me.
 
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old01cobra

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not to go off topic, but what mods you have.. healthy numbers man.


Block is a Boss stroked with dss flat tops, Fox Lake worked 03 heads with stock valves, 90mm maf with 60lb injectors, Fr500 intake top plated for a 96-98 with a return fuel setup and I cut the twin 57mm split out to fit a wide oval SVO tb from a 2000 cobra R with the intake flaps removed and made a fiber wrap 4 1/4 inlet tube running too the wheel well with some custom Bullet cams which were degreed. It put just under 460rwhp and 390 rwtq down. I do spin it too about 7500 rpm and I think I'm at about the limit of the cams I had ground, my calculations may have been off a taste because I wanted 475-500 rwhp but it is what it is now.

With a stock twin 57mm tb and the flaps installed with a factory 98 style inlet tube it made 433 and 376 and fell flat at 6500 till 6800 rpm. When I opened the intake It really let the thing breath with the revised top plate and the bigger inlet tube with the SVO tb plus it gave me another 1000rpm. I only spun the thing too about 7500 because at around 7200-300 it stayed flat till about 7500 so I either need bigger cams or I need too hog out the runners of the FR500. So it is what it is but yeah I think its healthy for a NA Modular it should surprise some LS guys.

How do you like the 4.30 gears? I just got a set that I will be doing shortly was going to go 4.56's but stepped back a little.
 

olgreydog7

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There's a good Engine Masters vid on youtube about that. Makes me want to go full 3 inch. If I ever get around to doing the bigger headers, I'll step up.

 

MagnaFlow

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Hi Old01, 2.5" piping will definitely be big enough to support your current power numbers. There'e no need to go 3 unless you just want more volume out of the exhaust.
 

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