Twin Cam 88/96/103 Performance Upgrades


The following performance upgrades are proven, dyno tested, reliable means of increasing the output of your stock Twin Cam HD. Many hours of research and development have gone into designing these upgrades using the most reliable parts available, combined with expert workmanship. These packages work! Other options are available (e.g.: different cams, different heads, etc.) that might also work very well but the fact is, our Stage 1 2 3 and 4 packages are dyno proven, hold together like OEM and will make your bike perform better than you ever thought possible. While we strive to keep on top of the performance game, and are open to input from outside sources, please don't call and ask "what if we use this instead" or "what can we do that is less expensive". These upgrades work. Period. Be confident in knowing that your bike will be getting top quality components in a package that makes real power (where you need it) - unlike glorified magazine claims made 2000 miles away in a different climate with different fuel compositions and riding conditions (or God forbid...some clown on an internet Harley Forum, sitting in his parent's basement in his pj's claiming to be an "expert").  Let's not even go there....   Now on to the good stuff!




Don't be misled by the constant emphasis placed on peak hp numbers at maximum rpm. This is not where most of your typical riding is done. Be more concerned with peak torque numbers and the rpm where maximum torque is produced. We are more concerned with the "area under the graph" after a dyno run to see how a bike is performing in real world riding conditions. Torque is what makes a bike fun to ride (not revving to 6500 rpm every shift for maximum hp). Remember: horsepower is an illusionary mathematical equation - torque is real and is everything that is good in the universe!

Note: for comparison purposes most stock TC88s make approx 58 hp and 70 ft lbs torque at the rear wheel. Power increases are expressed as a percentage rather than actual dyno numbers due to the many variables involved with different exhaust systems/carbs/fuel injection mods etc.  Stock TC96s make approx 66 hp and 85 ft lbs torque at the rear wheel.

STAGE 1 (approx power increase: 35% -based on HP since this is what most people are concerned with)

Stock pistons (88ci or 96ci). Andrews cams (special grind for BRONKO'S), adjustable pushrods, support plate bearing kit (if required), gaskets, carb re-jet or fuel injection mods (see note 1). This is by far the most popular package that we sell.

STAGE 2 (approx power increase: 45%)

95ci Big Bore kit for the TC88 (HD or Wiseco pistons 9.5:1 CR), Andrews cams (BRONKO'S grind), adjustable pushrods (optional), support plate bearing kit (if required), carb re-jet or fuel injection mods (see note 1). Carburetor upgrade optional (S&S Super E or Mikuni HSR 42).

STAGE 3 (approx power increase: 70%)

95ci Big Bore kit for the TC88 (HD or Wiseco pistons 9.5:1 CR), Stay Tuned Systems performance cylinder head rebuild (the best flowing heads in the business - yes Screamin Eagle heads cost a little less but do not perform as well), adjustable pushrods, Andrews cams (BRONKO'S grind), 07 and up HD camplate update kit (incl oil pump) S&S Super E or Mikuni HSR42 carb upgrade or fuel injection mods (see note 1)

STAGE 4 (approx power increase: 95%)

103ci Stroker Kit for the TC88. Big Bore Kit for the TC96. Call to discuss options and costs as this is a much more involved process than Stages 1, 2, or 3. This is the serious "go fast package". Big commitment involved here!


1. Fuel injection models for all stages require dyno time (usually at least 2 hours min @ $150.00/hr) to properly map fuel curves (for optimum performance) . 1999 to 2001 models see note 7. 2002 to 2005 models also require a Power Commander module. 2006 and up models do not need a PC - they require a HD Screamin Eagle Pro Super Tuner. The Power Commander is usually around $450.00, the Super Tuner around $540.00. Some bikes (those with Power Commanders) might also benefit from a HD Stage 2 chip/download as well, particularly if the bike is ridden hard to redline consistently. The chip's main benefit is in the increased rev limit. Most stock ignitions shut the engine off at 5400 to 5600 rpm. If your bike is making peak power at 5300rpm - and you ride in that range - you need a few hundred rpm of "override" before the rev limiter kicks in for peak performance. The chip raises the rev limit in the stock ignition. If you don't ride in this rpm range or if your bike makes peak power at say, 5100 rpm (so you already have a minimum of 300 rpm override) then you don't require the chip. HD's Super Tuner allows rev limit adjustments so no chip is needed for these applications. The HD chip/download usually runs around $225.00.

*NOTE: Power Commander has stated on their web-site that units bought over the internet (or from the US) and sold in Canada will have their warranty voided and Customer Support Services will not be available. This action is enforced through serial number information that must be provided to Power Commander for warranty or customer support.

2. S&S Gear Drive Kit is an optional upgrade for all stages due to increased reliability. The gear drive kit replaces the nylon ramps and related chains (which need to be replaced every 30 to 40,000kms in the TC88) in the cam case. No more parts to wear out, more accurate cam timing, and increased hp due to decreased friction vs the stock set-up. The Gear Drive Kit adds approximately $700.00 to the base price of either the Stage 1 or Stage 2 upgrade. Some bikes cannot accept a gear drive due to excessive pinion shaft runout from the factory. Your bike will have to be checked to see if it is a "candidate" for a gear drive set up.  An even better set up now is the BRONKO'S Update Kit which allows stock 07 and up components to be utilized.  OEM cam plate, oil pump, hydraulic tensioners, chains, etc.  This really is the "hot" set up for upgrading TC88s as it uses the ultra-reliable 07 and newer components.   Runs about $1400 (incl performance cams).  The HD Screamin Eagle Update Kit is not recommended for a variety of reasons (but is an option if you don't want performance cams and would like a partial upgrade from the stock set up).

3. Higher mileage engines (e.g.: 60,000 kms +) should also have the lifters replaced at the same time as the camshafts. The same goes for the stock cam chains, nylon ramps, bearings, etc. (this is where the benefit of the Bronko's Update Kit or gear drive kit becomes apparent).

4. Power Commanders work the best on fuel injected models (that require such). Other systems (such as the Vance & Hines Fuel Pak) do work but usually only get the mapping "close enough". While such systems may be easier to tune and might be more user friendly (normally advertised as "not needing expensive dyno time") we have found that the only way to achieve maximum performance is with a properly set up Power Commander. NOTE: 06 and up bikes require a HD Screamin Eagle Pro Super Tuner (in place of the Power Commander) as we have found that this works better than the Power Commander for these year bikes.

5. 2004 and 2005 TC88s will not perform as well as earlier and later Twin Cams due to the slightly poorer flowing heads that Harley decided to use for these years. They will still perform well but peak horsepower and torque numbers will be slightly down compared to 01-03 and 06 and up bikes (the latter having redesigned ports to improve flow even). The difference however, is extremely small and nothing to really worry about as the overall power increase is still fantastic!

6. FL and FXD series bikes (Twin Cam A engines that are rubber mounted) typically produce 5% more power on the dyno (compared to solid mounted Softail engines) due to less vibration (vibration causes parasitic losses through the drivetrain resulting in lower rear wheel horsepower numbers).

7. Magneti-Marelli fuel injection equipped models (FL touring series 99-01) are limited to upgrades due to the inefficiency of the stock fuel injection system design and related components. Please call to discuss options.

8. 2006 Dynas (and all 2007 and up bikes) employ a closed loop fuel injection system that utilizes 02 sensors. The best option so far for these bikes is a HD Screamin Eagle Pro Super Tuner that allows full adjust ability. Power Commanders do not work well on these applications. Small modifications (eg: mild exhaust and/or intake breather changes) do not require the purchase of a Super Tuner as the factory ECM and O2 sensors will compensate for the minor changes made (finally some good news!).

9.  For those with 07 and newer 96" Twin Cams we now have a new Andrews cam (special grind for BRONKO'S) that produces awesome torque (up to 109 ft lbs) and great hp (90+) when used with a decent exhaust and air cleaner!  Recent dyno testing has shown 100ft lbs of torque at only 2500 rpm when installed in a stock 2010 Street Glide with Vance and Hines true duals, Rineheart slip ons, and a Screamin Eagle air cleaner.  This makes for one incredible street motorcycle with ultra reliability!

10.  Tired of the excessive heat with your stock 103" and dismal horsepower and torque numbers?  We have found that 85+ hp and up to 110 ft lbs of torque can be had with your stock engine!  A reworked oem header system, a decent set of slip on mufflers, a free flow breather combined with a Screamin Eagle Pro Super Tuner and dyno tune is all you need to transform that 103 into the bike that it really should be.  The process isn't cheap, but well worth the effort (and again, with stock, ultra reliability).  Call for details.

*Lest we forget*
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