Rebate

Flowtech 11585FLT GM V6 O-Port Upright Headers, 1-1/2 In Primary

Rebate

Flowtech 11585FLT GM V6 O-Port Upright Headers, 1-1/2 In Primary
Flowtech Exhaust

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#42511585FLT

Flowtech 11585FLT GM V6 O-Port Upright Headers, 1-1/2 In Primary

  • Mandrel bent tubes provide consistent tubing diameters for better exhaust pulse flow and improved performance
  • 1-1/2 in. primary diameter for increased exhaust flow and improved throttle response
  • Heavy duty 16-gauge 409 Stainless Steel used for strength and durability
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$223.95

/kit

Factory Shipped

$249.95

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Product Summary

Upswept Header Tube Type, Round Exhaust Port Shape, Raw

  • Mandrel bent tubes provide consistent tubing diameters for better exhaust pulse flow and improved performance
  • 1-1/2 in. primary diameter for increased exhaust flow and improved throttle response
  • Heavy duty 16-gauge 409 Stainless Steel used for strength and durability
  • 10 in. long, 2.5 in. collector improves exhaust flow
  • 3/8 in. thick header flange for a leak-free seal and maximum strength

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Key Specs

MFG. Part #11585FLT
Header Tube TypeUpswept
Exhaust Port ShapeRound
Flange StyleStandard
Primary Tube Diameter1-1/2"
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Flowtech Exhaust 11585FLT Details

These Flowtech upright derby style headers fit the 2.8L, 3.1L and 3.4L GM V6 engines with both round port or D-port style exhaust ports. 1-1/2 in. and 1-5/8 in. mandrel bent primary tubes provide consistent tubing diameters for smooth flow of the exhaust pulses and increase the cylinder scavenging of the exhaust to improve engine breathing. The headers are constructed from heavy duty 16-gauge 409 stainless steel tubing for increased strength and durability. These headers use a 10 in. long, 2.5 in. collector with 20 in. long primary tubes. The 3/8 in. thick header flange provides a leak-free seal and maximizes strength.

Features:

  • Mandrel bent tubes provide consistent tubing diameters for better exhaust pulse flow and improved performance
  • 1-1/2 in. and 1-5/8 in. primary diameters available for increased exhaust flow and improved throttle response
  • Heavy duty 16-gauge 409 Stainless Steel used for strength and durability
  • 10 in. long, 2.5 in. collector improves exhaust flow
  • 3/8 in. thick header flange for a leak-free seal and maximum strength
  • Available for both round and D-port exhaust ports
  • Header gaskets included

Rebates

Holley October Promo 10% Off Select Parts Sale

Holley October Promo 10% Off Select Parts SaleHolleyOctoberPromo10%OffSelectPartsSale

Holley's October Promo 10% Off Select Parts Sale, running from September 28, 2026, through November 1, 2026. For a limited time, customers can save up to 10% off on select Holley parts, making it the perfect opportunity to upgrade your ride with premium Holley branded parts including Holley, Brawler, Quick Fuel, Leg Wheels, Rev Wheels, Rocket Racing, Flowtech, Edge, Racequip, Apr and Dinan. Purchases must be made between September 28, 2026, through November 1, 2026. This limited-time offer applies to qualifying Holley branded parts purchased during the promotional period. Following the promotion, these parts will revert back to standard pricing.

Guides & Documents

Choosing the Right Headers

CARB Warning

For race/ off road use only

Emissions warning: this part only legal for sale or use in California for racing (competition) vehicles which may never be used, registered, or licensed for use upon a public highway. Any other use renders the vehicle tampered and not legal for use on California public highways (any public street or roadway, public dirt road, public park, or publicly maintained right of way open to the use of the public for vehicular travel). Violations subject to $37,500 penalty per violation per vehicle, revocation of registration, loss of use on California public right of ways, and proof of correction for tampering. There are similar restrictions and penalties under federal law and the laws of all other states with penalties under federal law of up to approximately $45,268 per tampered vehicle and/or engine.
CA Prop 65
CARB warning

Flowtech Exhaust 11585FLT Specifications

KEY SPECS
MFG. Part #11585FLT
BrandFlowtech Exhaust
Header Tube TypeUpswept
Exhaust Port ShapeRound
Flange StyleStandard
Primary Tube Diameter1-1/2"
Material TypeStainless Steel
ColorNatural
Weld-UpNo
Collector Diameter2-1/2 Inch
FinishRaw
Hardware IncludedNo
Gasket(s) IncludedYes
Collector Reducers IncludedNo
Collector Attachment TypeSlip fit
GENERAL
Sold in QuantityPair
GTIN Code090127072943
Collector Length10"
Flange Thickness0.375"
Tube Length20"
TunedNo
Crossover Pipe IncludedNo
Primary Tube Gauge16-gauge
Transmission Mount IncludedNo
Catalytic Converter(s) IncludedNo
Motor Mounts IncludedNo

Questions & Answers

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Fitment

  • GM LC1 2.8

  • GM LB8 2.8

  • Gen 1 2.8 LH0

  • GM LH0 3.1

  • Gen 1 2.8 LH0

  • GM LB6 2.8

  • GM LH0 3.1

  • GM LA1 3.4

  • GM LH0 3.1

  • GM LH0 3.1

  • GM LQ1 3.4

  • GM L82 3.1

  • GM LQ1 3.4

  • GM L82 3.1

  • GM LH0 3.1

  • GM L82 3.1

  • GM LQ1 3.4

  • GM L82 3.1

  • GM LA1 3.4

  • GM LR2 2.8

  • GM LL2 2.8

  • GM LR2 2.8

  • GM LL2 2.8

  • GM LR2 2.8

  • GM LL2 2.8

  • GM LR2 2.8

  • GM LR2 2.8

  • GM LL2 2.8

  • GM LR2 2.8

  • GM LL2 2.8

  • GM LL2 2.8

  • GM LL2 2.8

  • GM LR2 2.8

  • GM L44 2.8

  • GM LB8 2.8

  • GM L82 3.1

  • GM LG8 3.1

  • GM LE2 2.8

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