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View Full Version : Header and exhaust size



ponchopwr70
12-05-2006, 05:42 AM
Now that winter is here and my car is in storage I'm making a list of things to do next year. I think my exhaust system isn't to great. Right now I have 1 5/8 dynomax headers (were coated but they rusted through so I painted them black.) My exhaust is 2 1/2" tubing with a kink on each side then flowmaster 40 series mufflers to 2 1/2" over the rear end then 3" tips that hang lower than the rear quater. I was thinking that i could at least use a x-pipe, or go all out and get 1 3/4 doug's headers coated with magnaflow system (not sure on 2 1/2" or 3".) The engine is a 388 chevy with 10.8:1 cr, gm 2.02 heads, z-28 intake dual plane, 750 holley, and cam with 507 lift 235 duration @ 50 and 108 lobe seperation. I dyno'd the car it made 318rwhp and 315rwtq corrected. I also have run 12.9 at 106 in the 1/4. What do you guys think? Thanks in advance.

ponchopwr70
12-27-2006, 05:18 AM
No opinions?

68Camaro
01-12-2007, 12:44 AM
The 3" system for sure, unless you want to quiet it down for some reason but the x-pipe will also do that.

ponchopwr70
01-12-2007, 05:03 AM
Thanks, I'm going to change my rockers also to 1.65, so should change lift to around .557. I was thinking 3" anyway because I'll proberly upgrade my engine in the future. I'm also going to get the 1-3/4 headers too.

andrewb70
01-12-2007, 06:35 AM
Dual 3 inch pipes is WAY overkill for your power level. Unless you want to spend money and not gain anything, what you have will carry you a long way before it becomes a restriction.

Andrew

6'9"Witha69
01-12-2007, 09:08 AM
Agreed. Bigger is not always better and in your case is overkill.

ponchopwr70
01-12-2007, 11:46 AM
So 2-1/2 magnaflow system will be better than my crappy kinked exhaust with flowmasters? So 3" is not needed and will have no power gain? My wallet is happier now.

6'9"Witha69
01-12-2007, 11:48 AM
The Magnaflow will do better and the 3" will not only be useless, but may hurt low end power. happy wallets rejoice!

Mark Smith
01-12-2007, 05:10 PM
thats kind of the system im looking to do with an ls1.2.5 with x member and magna flows.how do the magna flows sound?how do they compare with quieter flow masters?never have heard them.justy read that they flow pretty good.