u/johnnyappleseednh

I just bought a 1989 Mustang a couple weeks back and here is the setup(some things):

6.0 LQ9 87k SBE
Holley terminator x max (professionally tuned)
Team z tubular front end
Tranny cooler
70mm turbo on3 turbo kit
Built 8.8 rear end 3:73 gears 31 spline moser axles
4180E trans built w/ shift kit b&m slap shifter
All 6AN supply and return lines E85 capable
Aeromotive 340 in-tank pump
SVE Dual 12" electric fans
SVE 3-core aluminum radiator
Holley low ram intake
102mm throttle body
Holley fuel rails
Holley fuel regulator
10AN catch can system
Holley 48lb injectors
Stage 2 BTR cam
Endless suspension work: weld-in SBFC, re-enforced and double-plated torque boxes, full-tubular from strut towards foward, etc.

I was told by the previous owner that the car made 594RWHP @ 6psi on the dyno.

I have the vehicle back at the place that tuned it 18 months ago and they did a full vehicle inspection and are addressing an oil leak(its the rear main seal). They specialize in LS builds and come highly regarded.

Here is the recommendations based off my exhaustive list of questions, some recommendations you guys put me on, and really…. mostly their findings.

Aside from tons of little repairs and quality of life changes (moving the catch can, shortening the serpentine belt as it was chewing up the lower radiator hose, creating a proper dipstick, full coolant flush, replacing lower radiator hose, replacing the rear main seal, etc).

The two biggest additions would be going to a 95lb DeatschWerks Injectors and a 3600 stall FTI converter.

The injectors was something I was hyperfixated on because I want the car to be as safe as possible. At the end of the day, this is a “fun” “ice cream getter”, not something I’m racing but something I want to be able to get in, go-fast, scare the fuck out of some family and friends and have it be as reliable as possible. It’s supposed to be a fun street car that can be reliably beat on.

That being said, I’m sure in the future.. I’ll want some more power and I know those DW injectors give me some headroom. All of the fuel trims and AFR looked okay with the 48lbers.. AFR was always pretty solid… but I know it’s not optimal.

Before I make more power, I will be upgrading the 6AN and fuel pump but not now.. as this endeavor is already at $5,000 (the injectors and converter are approx $2,200 of this) and I paid $14k for the car(clean — needs paint but spotless rust wise… tons of unlisted suspension work.

The converter replacement is a TBD. They can’t get a part # or anything off of it until they pull the trans for the rear main.. but they believe it might be undersized because it does engage in rear pretty hard(might just be line pressure, but they hypothesized it might be an undersized converter) and the two-step is a bit wonky.

I wanted to know if anyone thinks there will be any noticeable difference with jumping up in injector size and converter and just general thoughts with the plan? Am I gonna notice anything in the seat of the pants or power wise?

Entire car was built by previous owner and has about 1,200 -1,500 miles on it now.

I just bought a 1989 Mustang a couple weeks back and here is the setup(some things):

Holley terminator x max tuned by horsepower farm

Team z tubular front end

Tranny cooler

70mm turbo on3 turbo kit

Built 8.8 rear end 3:73 gears 31 spline moser axles

4180E trans built w/ shift kit b&m slap shifter

All 6AN supply and return lines E85 capable

Areomotive 340 in tank pump

Dual 12" electric fans

3core aluminum radiator

Holley low ram intake

102mm throttle body

Holley fuel rails

Holley fuel regulator

10AN catch can system

Holley 48lb injectors

Stage 2 BTR cam

I have the vehicle back at the place that tuned it doing some quality of life changes and fixing an oil leak (rear main seal... yay).

I saw lots of pushback from you guys on the 48lbs(installed by the guy who built it)… it was dyno’d at 594rwhp @ 6psi in Nov 2024. All parameters look pretty good and they didn’t have much to say about it other than me mentioning it was something I got lots of pushback in the groups for — they do agree they’re maxed but probably safe right now.

I am considering stepping up injectors while I have the car there. They’re recommending 60lb injectors(don’t remember the brand). Is that sufficient in your opinion? Seems to be from some loose internet research and they’re the tuners.. but figured I’d ask here.

Goal is a 600whp — maybe 700whp someday — street car.. that may see the drag strips once in its life. HP Farm builds some monstrous vehicles and asked me this a few times so I’ll answer it here too, lol.

Also, they have to take the transmission out to do the rear main seal and mentioned part of the reason it could be engaging in reverse hard(something I asked them about, not egregious but ya) is due to a smaller converter.

The previous owner did not tell me the stall size, and they’re trying to figure it out now.. but likely won’t be able to until they get it out. They are recommending going to a FTI 3,000-3,200 for street use, but it’s mega expensive.

Any thoughts on that?

Any thoughts in general while I have it there would be nice, I’ve had them go through it with a fine tooth comb and don’t want the bill to get too out of hand, considering I just bought the car for $14k, lol.

All in right now, I’d be at like $4-5k for the rear main seal, injectors, converter change, moving the catch can a bit, fixing the serpentine that was rubbing on a coolant hose, replacing that coolant hose, replacing serpentine belt, full coolant flush, oil change, full transmission fluid change, and re-tuning it… plus a few other things I am forgetting. Trying to not get too out hand and that’s getting close, lol.