Tone Stack - Get rid of that farty bottom, honky mids, and lack of clarity. The result is an amp that sounds huge and warm with nice top end sparkle, not dark and buried in the mix.

Twin Mod - Fix the mids on the amp and get rid of that flabby bottom. This mod enables you to take all the mids out of the tone allowing more flexibility and versatility. This is accomplished with just a short jumper wire but the result is far better control of your tone.

Brightness - Like to play at low volumes but find the amp too dark? The brightness mod adds sparkle to your tone at low volumes. As you turn your amp up the brightness mod loses its effect so the amp never sounds brittle at high volumes.

Power Stiffening - Doubles the capacitance in the first filter stage, this reduces hum and increases reserve power for solid bass and better transience for incisive picking, This mod gives the amp the extra torque it needs to push through strong when you are playing hard. This also takes some stress off the output transformer increasing its life span.

Lead Master Volume - Ever wonder why this amp gets extremely loud after you turn it up past 2. Fender uses a linear taper pot for the Master Volume when it should be an audio taper. This mod gives you usable control of the drive channel so you can get good tone without playing at stadium volume.

Power Resistors- Many problems with the Hot Rod Deluxe, especially the older ones are from the power resistors that control switching. Two new power resistors installed properly will avoid many problems down the road.

Plate Load Resistors - Replace all the plate load resistors with high quality Metal Film resistors. This amp can develop a loud crackle/static that is caused by the plate load resistors. This mod fixes or prevents this problem.

Reverb Mod - Why does the reverb in this amp become a complete wash after turning it up past 3 especially at low volumes? This mod makes the reverb more controllable, fuller, and more natural. This is an easy mod that is nothing more than clipping one wire but the result is amazing.

Switchcraft Input Jack - Your input jacks are soldered directly to the circuit board, apply some tension when the amp is plugged in and you could cause major damage to the circuit board in the amp. This mod gets rid of the wimpy plastic input jacks and replaces them with high quality metal switchcraft jacks that are panel mounted and NOT directly soldered to the circuit board. Included is a shoulder washer and isolation washer so the input jacks do not ground directly to the chassis and prevents ground loops. 

Proper Lead Dress - Take a look inside a boutique tube amp and you will see all the wires carefully twisted and placed for greatest reduction in oscillation and noise. The Hot Rod Deluxe has all the internal wires zip tied together. I give clear instructions on dressing the leads inside the amp for optimal performance, this results in lower noise and less chance for oscillation.

Electrolytic Cap Upgrade - Replaces all of the power filter and cathode bypass caps with high quality filter and audio quality caps.  Older Hot Rods that are made in the USA are all getting due to have their filter caps replaced and many of the current Hot Rods  made in Mexico are known to have leaky filter caps.  The Fromel kit rectifies these issues.

Reviews:

*Just wanted to let you know that today I installed the Hot Rod Dlx "ultimate mod" kit I purchased from you on 19th Feb in my Hot Rod Dlx. The result has been, in a word, SENSATIONAL. The difference is like night and day. Installing these mods has taken a pretty decent mid price combo and raised it to the level of boutique quality tone.